Although i have never bought a snake from here

http://marketplace.thereptilereport....e/ball-pythons

i think it is a good place to get an idea of prices.

but you also have to consider where you are. For example i am in england and prices are as little higher than in usa. price is also affected by time of year. To get best possible prices the conventions are a good place because you have many breeders selling the prices have to be competitive.