I would hesitate as well in buying that BP.

I am definately not experienced in BP injuries, but from seeing other pics, it kinda looks like that scar is from a burn. But I may be totally wrong.

From the setup that he has been living in, as well as the scar, it seems to me that he has not been living in an ideal environment. This could mean future health problems for this guy. So unless you have some experience with rescue type BP's and are willing to possibly spend a bit at a qualified herp vet, I would pass. And please I am not trying to sound mean or harsh, I am just saying that that BP may be a little more than what you are expecting. I would go with a breeder as well, but that is only my opinion.