Another sales tactic to consider - put only one of the items up for auction, and if it sells for a decent amount, offer the second-highest bidder a "Second Chance Offer". If he/she accepts, you only have to pay final value fees on the second chance offer item - no listing fee.
This is an especially good idea if this is a relatively rare item, or something you know will get a lot of bids. It also preserves the perceived limited availability of the item if you only have one listed. People might bid less for an item if they know you have multiples up for sale (that's the theory, anyway).