How do you change an auction to a buy now listing on ebay without relisting the item?

I'm trying to sell my DS Lite right now and just realized that I should have put it under buy now but I put it under auction by mistake. If I re-list it I can make it Buy Now but then I get charge the listing fee again. Isn't there a way to just change it to a Buy Now listing? I was looking for it but couldn't find it. Any help is appreciated.