As it is a non-tangible item, I would say to list it as a Buy it Now, but offer maybe 25 available - this means that 25 people can buy the item before the listing ends.
With an auction you can offer a dutch auction for 25 where each of the bidder will get the item if enough are available. If you auction 1, then only 1 person will win the item at the highest price.
See
http://pages.ebay.com/help/sell/multiple.html for more info on multiple item auctions.
Personally, i would be tempted to ay extra for a featured auction of 1 item, starting at 1c and running for 10 days to guage an accurate final price of the item and to attract lots of attention to it, and then run a BIN listing with slightly lower selling price, but link the BIN listing from the auction - this way if people do not want to wait for the auction to end, or think it will end higher final bid, they can purchase the item straight away.
A featured listing costs £10-£20 in the UK, but can increase page views at least 5-fold. I list one fo my products on a featured auction about once a month, but it has 14 links in the listing, as well as the shop categories at the side, to entice buyers to look at other items for sale. Although may only break even on the featured listing, it tends to generate around £200-£250 of extra sales for similar products I have in my shop.