From everything I have seen/experienced, the standard for most bigger breeders seems to be 25% down, the balance to be paid within 30 days. For snakes over $500, some do 45 days. Over $1,000, and a particularly nice breeder might do 60 days.

Bottom line is how serious does the buyer seem ? They can put down the required down payment easily, and ask for a month or two to break the remainder down is good. They hem and haw about the down payment and then say it will take a couple of months or so to pay the rest, I'd pass.

Gale