While stock will always be changing, check the refruib and clearance sections of the major websites to see what they have. You may get an older machine that somebody returned or was scratched or something for a bit of a savings. Many of them will have 7 on them.

Companies like Dell also sell machines that have come off lease, so that's another place you may want to look at. Fewer and fewer companies are leasing laptops now (the cost is low enough to just buy them) so that doesn't offer the deals it use to, but if you get lucky and check right after somebody turns in a few dozen of exactly what you are looking for, you may be able to get a very good deal.