Prices on ANY 452s right now are flat-out ridiculous, even on Trainers. I've seen them for as much as $800 on a Trainer, and more for the Americans (depending on the wood). I think anything under $600 right now, is probably about right in this market. If things settle down a bit, maybe 500 isn't out of line.
I've been snapping up 455s whenever I find them at $400 or less. The 455s can be awfully good, too. I've rounded up a half-dozen of them, no complaints about them, either.