Rural King has been having an Omni (polymer receiver, I think) on sale for $475 to $500. I've seen mixed reviews on it, but it might be worth a look.
I picked up a Delton a year or two ago, less than $600 with iron sights, and haven't had any problems with it.
A guy here at work buys receivers and builds the rest, but he usually ends up with $500 to $800 in them, the advantage being you can end up with exactly what you want.
I don't think you can go too wrong, and if you end up with one you're not happy with you can probably sell it or trade it for minimal loss.
Good luck and take care.