Their "sale" simply eliminates on a few piddly items the tax you'd pay on it over simply buying it at another online Apple reseller where you're not slammed with hundreds of dollars in taxes.
As for the poster who asked about doubling down on the sale price AND the edu discount, if the post three years are any indication, no. Someone accurately pointed out that Apple rarely (read: Never) combines offers. There were some things I contemplated getting with my edu discount plus the xmas sale price, however they never would combine them. Last year I bought two Airport Express at the $99 sale price and specifically asked even the manager re: edu pricing and he said "Apple never discounts and item twice." Sooo with that, fat chance. Sorry.