Honestly barraguy, if you dont have money in hand from a buyer its still for sale. Im broke as a joke so when I see a part I really want, if I dont have the money yet I will ask the seller for a little time but if someone else comes along cash in hand, sell it. I wouldn't want somebody to wait on me if they have somebody willing to pay them right then and there.
But thats just my opinion. Most of the time when I had to do that, the seller put my name on it and didnt care if someone else came along with money.
Its your call