Americans are star-struck. Despite a modern world geared to fax messages and computer printouts, folks continue to vie for the good old-fashioned pen scrawls of celebrities who have reached the pinnacle in film, politics or sports.

Autographs from past and present keep increasing in value."Prices of top autographs are going up, with the highest prices being paid for the blue-chip choices," said Herman Dar-vick, autograph expert and author. "Academy Award winners, the presidency or Baseball Hall of Famers are examples in which you simply can't lose."

Collectors are everywhere. Two years ago, when this column noted that Darvick would provide a free assessment of an autograph's authenticity, he quickly received more than 500 requests from readers. (The offer still goes, if you send a photocopy and self-addressed stamped envelope to him at P.O. Box 467, Dept. AL, Rockville Center, New York, NY 11571.)

Film stars are in demand. An autograph of an established male star such as Mel Gibson, Sylvester Stallone, Harrison Ford or Tom Cruise brings more than $100, while a promising youngster such as River Phoenix is $25. For some reason, current female stars such as Meryl Streep aren't as much in demand.

While pop singer Madonna's autograph is popular, she's had a number of secretaries sign her name, so the collector must be careful. All autographs and letters of Marilyn Monroe are hot, commanding from $1,000 to many thousands of dollars, depending on how important or unique. Framing the autograph and putting a picture with it can triple the value.

"A handwritten letter is more valuable than a signature, though signed documents such as personal checks or typed letters on personal stationary are good," said Joseph Krause, editor of Autograph Collector's Magazine. "There are fads, with Christopher Reeve hot when the `Superman' film came out, and Michael Keaton and Kim Bassinger big right after `Batman.' "

In the sports world, baseball slugger Babe Ruth's signature sells for $750, compared with $75 a decade ago. Baseball card shows, in which stars show up to sign autographs for a price, have boosted values of sports autographs. Autographs of Jose Canseco of the Oakland A's and retired stars such as Mickey Mantle and Joe DiMaggio command the most dollars at these events.

"Collectors seeking historical autographs remain traditional, preferring presidents and famous generals, the American Revolution and the American Civil War," said Mary-Jo Kline, American historical manuscripts specialist at Sotheby's in New York. "A note from Robert E. Lee to Ulysses S. Grant the day of his surrender brought $200,000."

Auction prices are staggering. A record $440,000 was paid at a Christie's auction for a handwritten letter by Caeser Rodney, a signer of the Declaration of Independence, to his brother. Three chatty love letters from Ronald Reagan, signed "Ronnie," to a woman he dated before he met Nancy Davis sold together for $4,400. President Bush's autograph on a 31/2-by-21/2-inch White House card is worth $500, vs. $100 on regular paper. Soviet President Mikhail Gorbachev's autograph goes for $350. Unlike his predecessors, he'll send a signed photo to autograph seekers who send him letters.

For those seeking autographs of living celebrities, here are tips from Autograph Collector's Magazine, P.O. Box 55328, Stockton, CA 95205:

Collect autographs on 8-by-10-inch glossy photographs or 3-by-5-inch unruled index cards.

Obtain addresses from various Who's Who publications at your library, or from various books. You can receive autographs by writing a letter to the celebrity, including a photograph or card to sign. Always include a self-addressed stamped envelope.

Check your newspaper to see what events are in town that might give an opportunity for an in-person autograph. Always be polite and don't forget to say thank you.

Keep signed photos in three-ring binders with see-through sheet protectors. Index cards can be stored in photo albums. Never paste down anything.