The thing that I've found with Macs and anything Apple: if the deal sounds too good to be true, it's not! There are no deals on Macs. If you look through some of the threads, you'll see stuff on fraudulent Mac dealers and the scams that they try to pull. Best to play it safe with your money and buy from a reputable dealer if not Apple itself. When it comes to gift certs etc. I'd buy straight from the source.
Mick