Sometimes you can go to eBay and find plenty of used ballroom dresses that fit your criteria, but other times there is nothing that catches your eye. Instead of beating a dead horse, why not look when your chances of finding something is high?
For example, how about looking for a ballroom dress right after a major competition? You know that many couples scrambled and made their dressmakers work overtime to come up with a new look to impress the judges. But, after the competition is over, they might not want to wear them again, especially if they are a top level couple. This is when they will be looking for a way to sell them to raise money to buy the next one, or to reimburse their dressmaker sponsors.
During this time, you can get some really good deals. You can do it in one of two ways. One, you can simply attend some of these big competitions such as Blackpool in May or Ohio Star Ball in November, and tell the competitors that you are willing to buy their dresses. Or two, you can wait until dresses start hitting Internet websites such as eBay or other websites that sell ballroom dresses.