Asus SDRW-08D1S-U Slim External DVD±R/RW Drive (White) for $19.99 Shipped
Asus SDRW-08D1S-U Slim External DVD±R/RW Drive (White) for $19.99 shipped after submitting this $20 rebate. Here is a screenshot for your reference. This is very handy for netbooks which often do not come with a built-in DVD drive or burner. Most places have it for about $59.