Continue to watch ebay for a few months and you'll start to learn how to differentiate the inflated Buy It Now prices charged by parasite resellers from what games are actually worth. There's a number of BIN price categories on ebay:
1) totally ridiculous, insanely high BIN items (about half of everything you see...seriously);
2) everyday BIN prices (still WAY too high, like $50 sealed common games);
3) fair BIN items (sellers like SimpleSamson, West Exit (RIP), some DreamStars stuff (is Toshi still around?). These tend to get slowly bought up and resold by scumbags. 16-Bit is a decent seller that falls somewhere in-between 2 and 3.
4) dirt cheap holy grails that disappear in seconds ($20 US DE2, $200 for a boxed Duo with Godzilla, etc.
. Refresh your search button all-day, everyday and you might find one!
Finally, there's the prices that auctions actually close at. Be patient, wait for a real auction, and you'll get stuff for a fraction the price of the everyday BIN crap in category #2.
The real worth of a game can be determined by following these easy steps!
1) watch ten different auctions for the same game close over the course of a year.
2) average the total of the two cheapest copies that sold domestically (foreign exchange rates and shipping charges skew the results, duh)
You now know the actual worth of the game.
3) Wait six months for another copy to appear at this price.
4) Buy it.
5) Brag about if here.
6) Wait for Nat to tell you that you were ripped off and he found it for $100 less than the price you paid.