Not anymore, they changed how the market works. For set IOs (both recipes and enhancements) all levels use the same set of bids with the buyer receiving the item at the level they bid for. So if, for example, I list a level 32 Positron's Blast on the AH and someone wants to buy a level 50 version they can potentially buy mine and the game will convert it to a level 50 version.
Just curious..how do you know this? was it in patch notes somewhere?
Assuming it does work like that..what is stopping people listing stuff at low levels (like your Posi Blast) for HUGE amounts (say 50mil) then having a friend/dual boxed alt bid on the lvl 50 version, and getting it 'upgraded' for free? Obviously you would need to time it right, on an item with no other bids..but it could be done.
For instance, back before we could email yourself stuff, I had a lvl 20 Miracle on freedom, that I wanted for an alt on Virtue. I gave it to a friend of Free, had him list it for loads, and timed my bid just right. Then he just gave me back the money after.
Well first of all, that wouldn't be free, you'd lose the 10% listing fee. Second, a winning bid will always buy the LOWEST listed item that it could buy, so you'd just end up sending 50 mil to some stranger.