i dont see anything wrong with it, people trade snakes for things all the time from cars to services. if someone was willing to bet a snake they most likely would be willing to trade or sell the same snake. when a bet is made a value is put on what you put on the line, same as when you put a price on a bp for sale. if its wrong to bet them its wrong to sell them imo
I wouldn't personally do it, but you make a valid point. Also as long as both parties can provide proper housing/husbandry...why not?