The reason it's never been done is it's a stupid idea. If it's your "dream model" and it's worth $50, why in the he11 are you only bidding $10.99 and then crying that you lost it to an "evil sniper?" There is nothing preventing the early bidder from bidding $50 himself to keep from losing his "dream model" to that "evil sniper." Successful buyers bid once and bid their max.