I am in no way experienced in this sort of thing myself, but what I would tell this person is this. Ask them for a 25% deposit to guarantee them the animal. If they don't pay up, and if someone else inquires and is willing to put a down payment, then so be it.
This down payment allows them to prove they are willing to see the exchange through to the end.
Let's say that this person doesn't end up going to the show and flakes on the deal. You're out a months worth of food for two hatchlings(which isn't a lot but a loss either way) and time through which you could have directed your resources elsewhere. During this time you have also lost potential buyers.
The bottom line is, you can't always trust people on their word. If they do a down payment and then decide to brush off the deal. At least you have a 25% down payment to help cover costs of care during the time lost.
Hope this helps.
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