I might be missing something, but according to this the 1.5 TB and 1 TB are the same price.
1.5TB
http://www.amazon.com/Western-Digit...BMBY/ref=sr_1_6?ie=UTF8&qid=1299960483&sr=8-6
1 TB
http://www.amazon.com/Western-Digit...BMB4/ref=sr_1_1?ie=UTF8&qid=1299960835&sr=8-1
1.5TB
http://www.amazon.com/Western-Digit...BMBY/ref=sr_1_6?ie=UTF8&qid=1299960483&sr=8-6
1 TB
http://www.amazon.com/Western-Digit...BMB4/ref=sr_1_1?ie=UTF8&qid=1299960835&sr=8-1