From buyer's perspective, I like a payment plan.
From a seller's perspective, if you can sell all your merchandise quickly without offering a payment plan, then you are better off without it.

The payment plan however, is a good way to sell merchandise that isn't moving w/o having to put it on "sale." Markdowns cheapen your animals, everyone else's animals, and may miff some customers who recently paid you full price for animals of the same quality.

Colin Weaver (IIRC, that is his name...I can't remember his site name, but he had some very insightful business essays.) is worth reading for anyone in the reptile business. Worthwhile reading for any independent business person, actually.

I am not in this business. Nevertheless, one thing I notice scanning classifides like Kingsnake.com is some very low prices! I wish people valued their labor more. Why is any CB animal going for $30-$50? I haven't pencilled it out myself, but I can't imagine anyone is really making money when overhead costs are figured into these prices.

Just my two cents.