I don't think the Schrade knife values have stabilized yet. They went out of business in 2004, which created an initial demand, but also flooded the market with overstocks and people cleaning out their closets. Lately it seems the supply level has dropped, resulting in much higher prices for certain models.
So your best bet to find values is to search eBay. Compare your knives to recently completed auctions, in particular knives of the exact same model, of the same condition, and whether or not they have the original packaging.
-Bob