Not really. If the headline says free on eBay you can't add that the buyer must purchase 2 others in the fine print. That is a clearly a violation and will get you kicked off eBay. You may certainly offer all 3 games as a package deal and say somewhere in the body "its like getting the 3rd one free". Just don't put "free" in the headline.
I think so, sounds like a good sales strategy
of course :)
ebay sellers do it all the time
yes
Hi, I'm going to sell 2 Gameboy games on Ebay, and I want to offer third game for free to anyone who buys both games. Is this ok to do?