Prices are soaring these days, and if you're looking for ways to spend money, the sky's the limit. You can hire a helicopter or a blimp, fill the sky with balloons or a banner, or declare your own personal independence day with a fireworks display. Here's how. GHOSTWRITERS IN THE SKY. On a calm, clear day Aero Associates in Vienna (938-8029) will skywrite any message up to 17 letters or tow a banner with a message of up to 33 letters for $150 per flight. For the same price, Cohen Aviation of Churchton, Maryland, (301/867-3474) will trail a banner with up to 32 letters. Available for all occasions, Cohen's done graduations, weddings and even marriage proposals. (At the Preakness, it towed "Susan, will you marry me.") BLIMPY. Amusements Unlimited of Silver Spring (593-2900) will convey and 10' x 15' message you want smack on the sides of a blimp. The first in Washington to offer such a service, for $300 a day they'll hover at 100' over any building, shopping center or whatever, where permitted by FAA regulations. A little steep, but imagine the impression, lasting to be sure, you'll make with a big, fat "Mark, I love you," "Buy Harvey's Hamburgers" or "Happy Birthday, Mom." " FULL OF HOT AIR. Amusements Unlimited also provides, for $5, one hundred 9" multicolored balloons -- enough to fill a small portion of sky with blazing colors. It's $6 per hundred for 11" ones. A small tank of helium runs $28 and the regulator is $3. BUBBLES IN THE AIR. Blue Ridge Balloonport in Manassas (631-0423) and Ballooning Center of Northern Virginia in Oakton (620-3190) offer a combination of elegance and adventure with hour-and-a-half champagne flights for two at $175. CHOPPER-HOPPING. More conventionally, Pioneer Airlines (979-9170) will take you and a friend on a copter tour of town. The panorama with a twist -- you're on top this time -- is breathtaking. The freedom from buslines and sore feet almost makes the ride worth the $150 per hour. (BYO champagne.) HAPPY LANDINGS! If you're more the extrovert and itching for the personal touch, pilot your own sky traveler. Piedmont Aero of Manassas (631-0233) offers complete parts and accessories, flight instruction, air taxi, charter and hangar service. Their special Blue Sky Solo Call Course costs $329 and the result is your solo flight -- but no license. For that you need continued lessons at $1,200. MORE HAPPY LANDINGS. On a cloudless day in Somerville the sky over Hartwood Field is dotted with skydivers. A U.S. Parachute Association-affiliated center, this facility boasts ten years of commercial experience with an average of 500 students a year who dare a grand total of 4,000 to 5,000 jumps per season. A one-day program (four hours of instruction and a late-afternoon jump) runs $75 including equipment. Further jumps are only $20 each including equipment. Call 703/752-4784 for lessons or brochure. NOW FOR THE FIREWORKS. For real celestial sparkle, try Washington Fireworks Company (529-3352), whose aerial displays, generally bought by civic associations and other large groups, run $1,000 and up. TURKEY TAILS, ANYONE? Air Courier International is a worldwide company offering to carry almost anything almost anyplace by air. Based in Phoenix, but with a toll-free number (800/528-6070) it's served as agent for many of the top corporations on the globe, transporting the outrageous without question. It rushed R2D2 across Canada at a moment's notice, delivered hundreds of thousands of proxies to Alaska's Eskimos so the pipeline could be installed, brought 300 pounds of peanut butter to Italy and an entire 747-load of eggs to a hungry client. It regularly flies the Davis Cup in its own first-class seat and is busy sending 36,000 pounds of turkey tails to the Ivory Coast. THE BIG SHOW-OFF. For the wildly ostentatious: Majestic Air Service (656-1401) will take two couples from National Airport to New York City, where the pilot will wait while you take in a matinee, shop and have a late dinner. Afterwards, enjoy the city lights on your night flight home. The prop-jet trip, complete with onboard telephone and pilot, runs slightly over $500 per couple. Majestic will also arrange for a limousine at your destination.