You'll probably want 2 (or more) drives since even if you have the original discs the time needed to rip them again will justify the investment. On top of that you will most likely want a NAS to make the setup practical.

This adds up to a few hundred dollars that you wouldn't need to spend if the DRMs implemented were sane and reasonable with legal owners. And I don't even factor in the cost of the time, electrical power, or computing power involved to make it happen.