So if I understand you correctly; you already decided to buy it?
In that case, congrats!

If this woman really needs the money and she is a neighbour of your parents, I think you should take a look at the kingsnake classifieds what people are asking for albino burms (I guess it's around $125) and give her a little more.

For a burm this size I would give her $200.

Is this going to be your first burm?