Yeah you will be stuck with the 2 week return policy and maybe even a restocking fee? You can always get it at Best Buy and get their Buy Back program. Usually Best Buys retail prices for phones are higher than anywhere else, for example the Epic Touch runs 499 full price at Sprint and 699 at Best Buy. If you but it at Best buy and pay the 60 bucks for the Buy back (or 30 if you buy the Black Tie protection which in my opinion is a better deal than the TEP Sprint offers since there is no deductible and because they will give you either a loaner or a new phone immediately for the monthly fee of 9.99) then, if the pricing scheme stays the same you should get 350 bucks back that you can now spend on GS3. Best Buy will price match the lower Sprint price, so all in all, not that bad of a deal. After 6 months you only get 40% of the retail price, so 280.
It's some math worth playing with if you change phones frequently.