I have to agree with vestcoat. The short of it is you have to shop around. eBay is the last place I want to buy anything, but yeah I have scored some TG goods there. I've had good luck with GameTZ, CCGC, GameGavel, and eStarland. I've even bought some stuff off of what appeared to be a shady German website that ended up being legit (who knew?) and I ended up making a decent score. Many of the places you've mention I can't use, like Amazon, because they won't ship outside the U.S.A.
I'll tell you the best place for me has been here. I ended up winning Bonk's 3 in a raffle. A raffle! I grabbed World Sports Comp. from a member here, grabbed my Super System 3.0 card from a member here, and it goes on and on... I'm missing Magical Chase, and Legend of Tonma Hero which are both out of my price range. I picked up the PCE version of LoTH off eBay just to say I had it, and I'll probably get an Everdrive for MC. In short, this place has been great for me. It's taken a year and a half, but half the fun is the hunt.