Amazon has the Western Digital Caviar Blue 640 GB Bulk/OEM Hard Drive 3.5 Inch, 16 MB Cache, 7200 RPM SATA II WD6400AAKS for $58 with free shipping.
Technical Details:
* Brand Name: Western Digital
* Model: WD6400AAKS
* Hard Disk Size: 640 GB
* Warranty: 3 years warranty
* Hardware Platform: PC
* Hard Disk Description: Internal hard drive
* Form Factor: 3.5" x 1/3H
* Hard Disk Interface: Serial ATA
* Hard Disk Rotational Speed: 7200
* Buffer Size: 16 MB
* Width: 4 inches
* Depth: 5.8 inches
* Height: 1 inches
* Weight: 1.4 pounds
Amazon.com: Western Digital Caviar Blue 640 GB Bulk/OEM Hard Drive 3.5 Inch, 16 MB Cache, 7200 RPM SATA II WD6400AAKS: Electronics
Western Digital Caviar Blue WD6400AAKS 640GB 7200 RPM SATA Hard Drive $58 + FS 
