SNKNostalgia,
I've bid and won lots in the past. It can work out pretty well, though it takes a bit of research to see what the prices are for the items you plan to resell.
I've only purchased 2 large TG-16 lots, to keep what I want and resell the rest. It worked out alright. One time I managed to get games and stuff for free, the other I ended up paying for the games, though it was cheaper than purchasing seperate. I didn't lsit the games with BIN's, I set them for 0.99 and let them sell for whatever they raked in.
Funny thing was, 2-3 years ago I was bidding on a TG16 lot, that had terraforming, Bonk 3 CD, and a few other hard to find CD games.. The person who jacked up my bid, towards the higher end of my max (He almost won the lot) had SNK, or Neo Geo in his ebay handle. He actually sent me an e-mail after I won the auction, with something to the effect of, "I wanted that auction, but lost. hahahahhaa, but i sure made you pay for it." This thread reminded me of that... The one and only time I received a message from someone who had been bidding on an auction i won.
Some of the folks buying multiple copies of certain titles are almost certainly buying for stores, whether on or off ebay. Sometimes it also seems as though a person is trying to protect their investment, or "corner the market".
My suggestions; bid your highest bid and "walk away" from the auction, snipe, or look for BIN. Those 3 tend to work for me. You can also set Ebay to e-mail you when something appears for sale within a set search criteria, you may snag some nice BIN that way!