I think Wes summed it up.
I have a few rules, if someone is interested in a animal I have they need to put a deposit down regardless of past business dealings we might have had, too many times people say they are interested and than. So so long their is no money the animal remains available and keep being advertised.
After that (unless it's weather related) it's not like they can take the next 4, 5, 6 months to pay the animal of, the animal must be paid within timely manner (usually the terms agreed upon when making the down payment).
As time goes by 2 things happens
Price of mutations decrease
Your overhead (food and housing etc) will increase