You can't get student dev pricing any other way than direct from Apple. You'll have to pay sales tax.
The 17" Powerbook is $2,699+tax with the student discount.
It's $2,399+tax with the student developer discount. Figure in the $100 cost of membership and you're still saving $200 over the student discount.
Sounds worth it to me, unless you'd rather just give me the $200.