Collecting cartoon art isn't kid stuff - at least not when prime examples regularly sell in the five- and six-figure range. What was once a low-key market attracting nostalgic collectors with a soft spot for whimsy has now become a highly competitive field, where characters like Mickey, Jiminy, Dumbo and Daffy share the auction-house limelight with names like Windsor, Tiffany, Wright and Shaker.

According to Frank Donegan, writing in the December issue of Americana magazine, devotees covet cartoon cels - the artist's rendition of a character that is traced or photocopied into a clear plastic sheet, colored and then mounted against a watercolor background. Thousands of cels are required for a full-length feature film such as "Snow White" or "Sleeping Beauty." Cels fetching the highest prices are those that are still secured to their background mounts and that portray important scenes in the film. Classic moments from well-loved Disney films currently generate most of the activity in the higher-priced area of the market. A cel showing the title characters Lady and the Tramp being serenaded over a spaghetti dinner recently sold for $104,500, and one of Jiminy Cricket dancing on a violin in a scene from "Pinocchio" went at auction for $57,000.But that's not all folks! Not surprisingly, the most valuable cels are black and white ones from the 1930s, when that lovable mouse Mickey was introduced. Such cels are much rarer, and prices are accordingly steeper. One such cel, from the 1934 short feature "Orphan's Benefit," sold privately for a reported $450,000 and another went for $286,000.

Favorite non-Disney character cels reportedly sell for thousands of dollars, especially those shown in theaters during the 1940s. The Warner Brothers characters - Bugs Bunny, Daffy Duck, Elmer Fudd and their many Looney Tunes peers - are rare because the studio destroyed many of those vintage cels. Examples from the 1940s can bring up to $10,000, and later cels range from $800 to $2,500.

Because they are in much less demand, cels from Disney films of the 1960s to 1980s are an excellent starting point for novice collectors. Donegan notes that the apparent lack of interest in films such as "Jungle Book" and "Aristocats" may be only a current phenomenon. Children who viewed them aren't yet old enough to wax nostalgic about them.

Recently Disney films like "The Little Mermaid" and "Who Framed Roger Rabbit" offer some exciting collecting possibilities. They exhibit a standard of animation worthy of the older films, and cels from them are scarce because Disney is releasing only a limited amount of material.

Oddly enough, the animation drawings from which cels are traced are not popular in this market. Neither are cels from television cartoons, although there is some interest in "The Flintstones" and "The Jetsons."

What enchanted millions of children in the past, however, is not the sure-fire gauge of what will do the same for future generations. When Donegan asked animation expert Joshua Arfer what he might buy for future investment, he promptly replied: "Cels from `The Simpsons.' "