When you donate clothes to one of the used clothing chains around here, they give you a voucher for a discount on buying their clothes. That's as good as I've been able to do, and I think you might find it difficult to do any better unfortunately. New clothes are just too cheap, and the sizes and selection available are huge, so most folks don't buy used.
My most expensive articles of clothing are custom made pants/shirts for work (I am an odd size person) but those would be impossible to sell as a result.