Yea I'd go ahead and bet again on the turn. The lack of a flush and two callers is frightening, but go ahead and half pot it again. There are still TJish straight draws out there that they could have been chasing plus just noobish calls (it is thanksgiving break for a lot of fishies). If its a set, you'll know on the turn and can fold. If they call a 15 dollar bet on the turn, then fold the river if they do anything wild. its ok.