This.
Art collectors tend to get intoxicated at the idea of getting something from an artist and leap before they look into things like they should. I have been guilty of this myself. You see a commission opportunity and you get tunnel vision and before you know it, you are pushing money at them without setting up parameters/protection that you should.
Art is about passion and that can lead to financial decisions that you wouldn't make anywhere else in life. I just got a new roof on my house and had 5 companies out for bids, researched them all intensively, and then made an informed decision and they agreed to take payment upon completion. Sometimes we as collectors need to take more heed before jumping into a commission, especially when it is very expensive.