The thing of it is that most of us think of a prom dress costing at least 150.00 but then we only wear it once.
there are some good costumes that would make great prom dresses and they start at about $45.00
wedding dresses
wedding gowns
custom wedding dresses
You can find these at uniquepromdresses.net/gothic-prom-dresses.html, then click on any of the images to get to the costume sites.
Unique Prom Dresses is one of the best resources for cheap prom dresses on the net.
I guess you could try and sell it after that on Ebay or something... but you would have to be early in prom season to sell it for a decent price.
Have Fun!
Robin