It varies hugely depending on the breeder, the animal, and just on the time of year, supply and demand, what else is available at the show. If a breeder goes with a certain snake and it turns out that there are hundreds of them available he may lower his prices to be competitive, if he realises his is the only one there he may well raise his prices. A lot of breeders don't price their boxes for this reason, and it's up to you to ask - and then haggle. A lot will reduce prices at the end of the day for things still left.
If you know what you're looking for I'm sure someone can give you a rough price range but as for snakes well anything from 5 euro to 5000 euro and beyond!
__________________
Feel free to PM or call our store for advice if you need help on housing or care of any snake, lizard or tortoise.