Maybe you didn't get the whole story... I had a situation once where I sold an arcade game. Buyer paid and setup shipping.
Then the damn monitor went out. So, I explained the issue and said he could have a full refund. We ended up settling on a reduced price.
Just saying... Maybe find out what the reason is for backing out before publicly complaining about your transaction woes.
If it is just cold feet.. I agree; dick move.