Staples sometimes sends discount certificates. Or you can buy one for cheap at ebay.

I got a $20 off $100 certificate in my email from Staples. I got:
MONEY PLUS DELUXE 2008 Price: $39.99
WINDOWS LIVE ONECARE 2 Price: $39.99
TAXCUT PREMIUM FED Price: $19.99
TAPE DISPENSER CORE-CLEAR Price: $.28

Subtotal: $100.25
Delivery: FREE
Coupon: -$20.00
Tax: $4.01
Total: $84.26

I will get $80 in rebates and about 1000 airline miles (credit card + portal miles + portal bonus)