If it was for a week or two I would refund it, I've done it before, but once you stretch it into months it's a no-go. There are a lot of buyers out there who just string people along. I knew one dude who actually admitted to me he did this. He would string multiple sellers along for a long time, saying he was waiting on money etc., locking up all the machines for himself. Sometimes he would end up buying SOMETHING, but it was always the best deal out of them all. He actually did this to me a couple times, trying to hold me to months old deals while the prices were going up rapidly, but even then he wasn't ready to buy yet!
Keep the money!