Anywho - my ADVICE to the OP is this: have the snake sexed and weighed by either a vet or a reliable breeder, if you feel this is necessary. If you're not going to be involved in breeding, sex and size won't matter, right?
If you just want the snake for a pet, go ahead and buy him/her, PROVIDED the BP is healthy. You don't want to lay down 100-250 bucks - whatever the person is asking for - and find the snake has intestinal or respiritory problems, or mites.
Mites are a kick in the pants, trust me.