I've had people want me to drive 2 hours to deliver a $5 rat for free. Umm no.
Basically I don't consider any animal sold until it's paid for and no animal gets held without a nonrefundable deposit.
Like someone else said, everything else is just an inquiry. The response to someone who says "Can you hold it until...." or "I'll have the money on...." is "The animal will be for sale until I have payment"