How Much Is A Signed Copy of The Comic "Stormwatch" Worth?

You didn't say which issue it is, but based on the year, the comic would be one of the first 6 issues. According to www.comicspriceguide.com, the value would be $2.50 (any of the issues). Looking at some of the online stores, they are selling the comics for a little over $1. The signatures will probably not help much. First, you would need a certificate of authenticity to prove the signatures are real. If the signatures are valid, then the value is only what someone is willing to pay for it.