Amazon Warehouse deals has one for under $500 listed as like new. You wont find anything better for the price. It has a Core-i7, GT 540m, 1920x1080, 6GB RAM, and 500GB HDD. I understand if you don't want a used one, though. You will have 30 days to return it if you decide that you don't like it.
Otherwise, any Asus with a i5 would work well. I prefer Asus because they're one of the best brands for reliability, and they come with at least one year of accidental damage protection as part of the manufacture warranty.