Pricecharting.com prices typically only work well (for fast sales) on the really rare stuff.
Ikari warriors for example, not an easy game to find so it sold right away. You don't get a lot of options on that one (at least ones that aren't grossly overpriced)
-Pete Rose Baseball $24
-Double Dragon $34
-Donkey Kong Junior $15
-Title Match $28
-Super SkateBoardin $37
-Impossible Mission $29
Are somewhat easier to find, or very easy in some cases. Basically they don't sell instantly at the going rate on pricecharting...
While the prices might not be too far off, or even dead on in some cases, they aren't going to sell immediately at those prices, you will need to wait for someone looking for them...and hope a cheaper option isn't available to them. If you look at the completed history on ebay, you can see a lot of those sellers had that game for sale in their possession for awhile/etc.. they got top dollar, but they waited for it.
Basically, if you want stuff to move fast (like I typically do) you need to go 60-70% of the going rate. Either a collector will snatch them up, or a reseller that wants to deal with the work and time involved for the extra 30/40% return.
Hope that helps