These days fitness seems to have a higher price than ever. Annual dues at a fancy, mirrored health club can easily run into hundreds of dollars. Driving across town to an exercise studio in the rain or snow consumes valuable time and often interferes with your busy schedule.

But whether you're a casual jogger or an Olympic wrestler, you can work out at home and achieve a health spa's results for a much lower price. Of course, what you save in time and money you'll have to make up in self-motivation and by finding gym space in your living quarters. Once you own a home gym, however, you can work out whenever the mood hits you, and you'll never have to fight a crowd.

The cost of home equipment can range from as little as $30 for a jump rope and two medium-weight dumbbells to more than $25,000 for a complete set of Nautilus machines. A home setup can cover an entire family room or be stashed into the corner of an efficiency apartment.

Your gym can be as elaborate as you want, but fitness experts say only two items are essential: an aerobic conditioning system, to build and maintain a strong heart and lungs, and some form of resistance exercise to develop muscular strength. The Basic Gym

You can develop the rock-hard body of a Marine with nothing more than a doggedly pursued program of calisthenics and running in place. But assuming you want some equipment for your home workouts, a sturdy jump rope would be a fine choice for aerobic conditioning, and a 110-pound set of steel weights is the best buy for resistance training.

"Your heart doesn't care how it gets its exercise and circulation, just so it gets it in some form on a regular basis," says Dr. Gabe Mirkin, a Georgetown University fitness expert. "You don't have to spend a lot at all. You can jump rope, jog or run in place. It doesn't have to be fancy to be effective."

But even the simplest home equipment should be of good quality. Spend $14 for a leather jump rope and buy steel weights, not vinyl-covered cement ones that will crack someday. A set of good steel weights can be found at nearly any sporting goods store or gym supply company at prices ranging from $45 to $100.

Also remember that even the most expensive equipment is worthless unless you know how to use it properly. Spend a few dollars more for a paperback book outlining a program that looks interesting to you and follow its instructions carefully.

If you lack the space for a full set of weights or prefer a somewhat lighter workout, look for a set of dumbbells. They are available in either single pieces or with variable weights that can be assembled on the bar, just like a barbell. Dumbbells should cost between $1 and $1.50 per pound.

If you have a little more money and space, the next item for your gym should be a simple weight bench. For $45, you can own a solid model that will help you build strong arms and chest muscles.

It is worth noting that experienced salesmen and the experts advise against buying the leg machine attachments sometimes offered with basic benches. The slight benefits you derive from the leg extension and leg curl devices sold as add-ons will almost certainly be offset by disappointment with the lack of comfort and the shakiness in the contraption when you work out. It's better to save up for a sturdier bench or separate leg machine.

If you want to add one more twist, you may consider a chin-up bar for strength and a set of wrist weights, such as Heavy Hands, for your aerobic routine. A chin-up bar costs between $14 and $50, and wrist weights start at about $18. The $350 Gym

For those on a moderate budget but with some extra space, a sturdy stationary bicycle is recommended by the fitness pros.

"Just make sure you get a solid bike with a heavy flywheel. Most of the bikes on the market are junk and people who buy them are wasting their money," says Mirkin, who rides a stationary bike as part of his exercise regimen at home. Plan to spend at least $300 for a good quality machine.

Other features to look for on stationary bikes are steel construction and a solid, comfortable seat that won't slip out of position. Pay close attention to the strap that fits around the flywheel and spins it. On less expensive models, those straps are made of cotton cloth or rubber. Make certain yours is made of nylon.

An alternative aerobic device with a reasonable price is the rowing machine. Rugged rowing machines start at about $180 and "are the best thing around for strengthening your back muscles," according to Mirkin. Remember, though, that a rowing machine is for toning and aerobic fitness; it won't build big muscles despite what promotional brochures may say.

After a rowing machine or stationary bike, your next investment for this price range should be a more solid bench that widens the variety of exercises you can do with weights. Plan to spend from $160 to $340, depending on sturdiness and number of exercise options. The $600 Gym

For $600, you can buy a high-tech resistance machine that builds muscle without using weights. The best-known models are made by Soloflex, Pro Form and DP Inc. Soloflex uses synthetic rubber weight straps to provide varying tension between its movable bar and stationary steel spine. Free weights can also be added to the bar for a more difficult workout. Pro Form's model, advertised as Kong, relies on thick springs for tension. DP uses rubberized straps.

None of those machines offers the full range of motion or firm resistance you can get with free weights, but they are relatively light, very compact, and look like a piece of modern furniture in an apartment. If you use them, you can jog or jump rope for an aerobic workout.

"The biggest advantage is that I can use it whenever I have a few spare minutes, and I never have to load up a bar with weights," says Dr. Rozier Detweiler, an Annandale physician who has been using a Soloflex machine since last March. "It's perfect for me because I'm frequently on call and I work late at least a couple of nights a week."

But the convenience of these machines is offset by their uneven tension, which, unlike weights, changes through the push and pull of each exercise. "It's not a smooth motion," says Mirkin. "It's better used as a toning machine."

There are portable home weight machines available in this price range, but most experts caution that they are less sturdy and comfortable than the more expensive versions. "I wouldn't recommend them for anyone unless they consider lack of space to be their most important concern," says John Miller of Gold's Gym in Wheaton. "The range of motion of these machines is limited and not everybody fits the size body they were made for." The $1,200 Gym

Solid, comfortable weight machines with at least three workout stations start at about $1,200. If you have the room and the money, experts say these are the ideal systems to use. With sturdy leg stations, high quality weight machines build the lower body parts much better and more safely than free weights can. Changing weight for each exercise is as easy as shifting a metal pin in the weight stack, and variety of movements can reach two dozen on some of the better-engineered machines.

"You don't get the perfect, full range of motion on exercises like the biceps curl and military press that you do with free weights, but for so many different exercises and the added safety, it's worth the money," says Charles Miller, a chiropractor and fitness buff who owns American Physical Fitness Co., a chain of gym supply stores. Miller uses free weights at home because he lacks space for a complete machine. "I'd have one if my apartment was big enough," he says.

It is important to shop around and carefully test a machine before you buy it. Make sure the bench press is solid and that you comfortably fit into each station. Inspect pulleys closely to see that they are of one-piece construction and not just two wheels screwed together. Look for smooth, top-notch welding jobs on the corners.

Above all, don't buy a weight machine through a mail order house unless you have tried out an identical model. The Money-Is-No-Object Gym

The best quality, heavy-duty weight machines can cost up to $6,000. With that extra expense, you should be getting additional stations, such as sit-up board and separate leg press and a leg extension machine.

(Those for whom both money and space are really no object can consider a set of Nautilus machines, now numbering about 30, each carrying a price tag of at least $800 and each designed for only one or two movements. For most people, the only practical way to use the full range of Nautilus equipment is to join a health club.)

Even in the highest-price category, the basic training principle remains the same as if you were spending