Issue selling character on warmane trade

I promise I looked this up first.

When creating a new character for sale, I get the error "A minimum of 5 coins is required to sell via the trading system, you have donated for 0". I read that the service fee is NOT applied up front, but taken out of the sale price at the end instead. Is that wrong? Is it just requiring that I've made some sort of real money donation? How much is required?

You must have donated for 5 coins. They won't be touched during the transaction (whether it expires or the character is sold) but you must have paid for them.