windsolar, nice tractor at a great price. However, you better hope the seller has some integrity. Giving him $20 to hold an $18,000 dollar tractor is on the "I really want it, but I don't have the funds right now--I'll try to get it" side.
If someone else sees the ad, and comes by he may very well move you out of the picture by offering the asking price and paying.
It unethical, but in our society of everyone for themselves, it happens all the time.
I wouldn't be posting and stating facts on the internet until it's in my barn!!
Hope it works out for you, nice machine.