Paid sellers can sell an entire set in individual auctions in just a few clicks. Everything else is listed as normal, but the title and body of the auction are adjusted for each card individually.

A screen in the middle is used to adjust the quantities of any card, so if you are missing a few, you can zero them out.

Note: You have to drill down to exact set/rarity level each time, but if you are breaking up sets, it is an extremely valuable tool.