Paying for a Purim costume

Two years ago I dressed up for Purim for the first time since I was little. The outfit cost me nothing, given that I was planning to dye my hair anyway. This year, though, I can't pull off that trick again. There is, however, a Purim costumes shop in Hendon; costumes are available for as little as £12, which is rather less than fancy dress I've seen on sale online. However, I don't feel comfortable about splashing out money, particular as I'm unlikely to want to wear the outfit again on subsequent years, and would therefore end up forking out money each year for something I'd only get a single day's use out of. This feels wrong, somehow, and not in keeping with the spirit of Purim.

Thoughts, anyone?