Today on my warrior I needed the +12 strength enchant to my Guardians Bracers.
I was broke at the time seeing as I only had about 10g, which I was planning on saving for repairs.
So I typed the following in LFG. "LF Enchanter for +12 Strength to bracers, I am broke atm but I will pay you 60g tomorrow." (Depending on the enchant say more money, a good idea would probably be 2x the amount it's worth)
This was a half hearted attempt on my part, but surprisingly it worked. About 5 seconds later I got about 4 whispers. I shift clicked on all of them to see what level they were ect, I decided to go with the one without a guild because guildless people are usually less serious players.
After I got the enchant, I reassured him I would pay him 60g (I DID NOT SPECIFY WHEN!) and told him to add me to friends.
This sounds like it would NOT work, but it does, and before you flame me you should try it yourself.
When they whisper you tell them that you'll pay them eventually, then ignore them.