Where can i buy a pre-Flashed Xbox 360 DVD Drive?

I was wondering if there is anywhere i could buy a pre-Flashed DVD Drive for Xbox 360? Im needing one to play burned Games and i was wondering if you could buy one without having to do it yourself?

Ive seen a mail in service but its on a website ive never heard of with a user that has n/a feedback/rep so i would like a better source of mail in or just buy one.

Thanks Guys.