Mention Science Fiction and many people think of Star Wars or Star Trek, but SciFi actually has a history stretching back over one hundred years to Jules Verne (1828-1950) and H.G. Wells (1866-1946). It does not matter, however, whether you're buying or selling first editions of Verne's or Well's books, Buck Rogers ray guns, or Spock ears, the laws of the market are the same: scarcity and condition are the two most important factors in the price of any object.

When dealing with scifi books, keep the following in mind:

1. First editions of popular titles by any one author are generally worth more than those that are obscure. Thus, all other things being equal, a first edition of Well's The Time Machine can command a higher price than his Men Like Gods.

2. Alterations result in scarcity. A somewhat recent example is Killing Time (a Star Trek paperback) by Della Van Hise. A number of paragraphs in the 1985 first printing were excised from subsequent printings. The first edition, with raised lettering on the cover, is now worth at least twice as much as first editions of other Star Trek titles.

3. A dust jacket in good condition adds value, especially if the artwork is particularly striking or by a well-known scifi artist.

4. Autographed copies are always worth more than unsigned books. (The owner's signature in a book will usually detract from the price, unless the owner is someone famous, like Marilyn Monroe or Elvis Presley.)

5. Condition, condition, condition. Everyone wants as close to mint condition as possible--just like every other collectible. Coffee stains, ink marks, tears, and creases all decrease a books value.

If you're curious as to the values of out-of-print books, you can check the completed auctions on eBay, or sites like http://www.bibliofind.com, which lists thousands of used books by various dealers.