Most Fabricators aren't worth anything, unless it's for popular weapons like Rocket Launcher, Minigun, Flamethrower, Holiday Punch, Knife, etc, it's the actual KITS themselves that are much more valuable. For example, a Professional Killstreak Minigun Kit can land you about 12 - 14 keys, Rocket Launcher 20 keys easily, etc. You should use Backpack.TF for price range of kits themselves, and for some, the fabricators.