If you have less than an entire deck of cards, sell them individually, and space out the auctions. That would drive more interest than selling what's perceived as an incomplete product.
(I've sometimes had a hard time getting my head around eBay selling practices. Back around 1999 or so, someone associated with the Atlanta Braves got ahold of a pile of game-worn jerseys, and decided to sell all of them at once, with auctions ending within ten minutes of one another. I bid on a couple knowing I had backup plans. And that's why I have an Alan Embree jersey in my closet right now.)