I think the boa pictured is a nice hypo, NOT a super.
I think the price is OK, but the buyer has to make that choice. Hypos can be purchased cheaper.
It could indeed be het/but the seller didn't offer any guarantee of any kind. Sounds like he bought it as a possible het?????maybe purchased as a possible super??????? If he paid for a super hypo het albino he would value it for more than $350.
Let us know if you buy him.