How much does (insert snake species here) cost?
Unfortunately that is a question that can't be answered in a generic round-about way. The best thing to do is to get a hold of a couple of different breeders who specialize in the species of snake you are interested in and ask them what their current prices are. Be sure to specify anything special you're looking for (eg: designer morphs, adults or babies, male or female, etc) so they can give you the most accurate information.
Also keep in mind that prices do change and most breeders have a "lock in" policy. That just means that until you agree to buy the animal and put a deposit down on it there is a potential for the price to go up or down.
There are also several websites online that serve as "trading posts" for snake sellers and buyers. The two that are the most active are:
You can almost certain find the information on pricing you are looking for there if you take a few minutes to look around.