This deal has ended.
Normally $100 or higher, Toys R Us now has the 20GB Hard Drive for XBox 360 on sale for just $49.98. Use the "Bill Me Later" option and receive an additional $10 discount, lowering it to $39.98. This hard drive allows an additional 20 gigs of memory for gaming, music, and video. Shipping is currently free (regularly $4.99), and taxes vary by state.