This deal has ended.
Through 12/22, Buy.com has the 1TB Cavalry External Hard Drive (model CAUM3701T0) on sale for $99.99 after this $20 mail-in rebate. Plus, delivery is free and there is no sales tax (except CA, MA, MD, NY, TN). This features one-touch backup and you're paying less than $0.13 per gig. There are also additional discounts: if you spend $0.01 more, you can get $20 back via Bill Me Later, or checkout via PayPal and get $5 off.