YMMV, but here's my situ.
I have a student ID, I'm researching the MacBook White, Superdrive, with 1gb (or 1.2gb) memory. My findings: Apple Store wins, despite tax crap.
All shipping was free (inc. the RAM).
1) Apple Store (Edu)
1380 inc PA tax: Computer + 1 gig ram matched pairs + 60 gb hdd
1380 total.
2) Amazon
1200 inc rebate: Computer + 512 mb ram + 60 gb hdd
0174 inc PA tax: Crucial 1gb stick
1374 plus installation and rebate headaches, total
Yakov.