It's vacation time, and if you're on a limited budget, you have to hunt for bargains.

Several airlines, hotel chains and others are aiming special package deals at the so-called "graying" travel market. For example, TAP (a Portuguese airline) and Iberia (Spain's airline) are offering special package tours to beach resorts in southern Spain and Portugal.

Most of this summer's packages are booked up, but look for openings from September on for a two-week up to Portugal's Algarve and Spain's Costa del Sol beaches. For $389 (from New York), you get air fare on a regularly scheduled flight, a deluxe apartment in the beach resorts and all transportation to and from airports.

The package has special low-cost add-on fares for passengers departing from other U.S. cities. For example, to make connections from Chicago to New York, you'd pay only $63 air fare (compared with $137 regular fare). Vacationers who want to stay longer in Spain and Portugal, can add up to a total of eight weeks at $35 a week extra.

Incentur is handling the packaging and can be reached at a toll-free number: 800-223-5537 (within the city of New York, call 832-0982).

Groups Unlimited is offering bus tours throughout the U.S. and Canada through travel agents. For example, a six-day tour through Canada's French-speaking Quebec Province costs $306. The price includes bus fare, hotels, five breakfasts and dinners and one lunch.

The American Hotel and Motel Association says various members are now offering special discounts to senior citizens. Among those listed are Best Western (Canada). Days Inns of America, Ramada Inns (if you're a member of a national retired or senior citizen organization), some Sheraton Hotels, and the resort hotel in Hershey, Pennsylvania. Most offer 10 percent off, but participating Sheraton hotels offer 25 percent off.

Gomer's Guide is a paperback book that lists budget motels and hotels with special discounts for the elderly. It costs $3.95 in bookstores, or you can send a $4.45 mail order to: Hammond, Inc., Maplewood, N.J. 07040.

Orlando, Florida, has a whole list of hotels, motels, restaurants and other attractions that offer discounts to senior citizens. For more information, write the Orlando Chamber of Commerce, Orlando, Florida.

A number of colleges and universities are presenting special vacation packages for senior citizens and others to use their facilities this summer. You get inexpensive rooms, low-cost meals and the use of swimming pools, tennis courts and other facilities. Some offer special classes as well.

Some senior centers, religious organizations and clubs are organizing "vacation swap" deals in which you take over someone's apartment in another city and they take over yours. The organizations sponsor special tours, meals, parties and events for the swap visitors. Perhaps your organization could try it.

Some centers are organizing low-cost summer camps for elderly members. For example, Vacations and Senior Centers Association in New York City offers low-cost camp vacations for people ranging in age from 55 to 90. You get boating, swimming, meals, crafts, music and all that fresh air and camp-fire food.

The Pennsylvania Department of Agriculture sponsors farm vacations for city slickers - a week in the country to watch the milking, haying and other farm activities. If the fiddler's fit, you might even get an old-fashioned hoe-down with square dancing and plenty of good company.

Q: I'm considering enlisting in a company's in-home sales program to make extra money. Is there anything to look out for? I certainly don't want to lose any money.

A: Do you have to invest a considerable amount of money? Is it a product that's popular, one you'd like to buy? Is there a buy-back agreement for inventory you can't sell? These are just some of the questions you should ask.