I'm in talks with a seller that has a lot with a "house" on it that needs to be razed?

The "house" was used to store the gentleman's tools & boy does he have a zillion of them. The house/structure has water & electrical, but the house will have to be torn down to build a new house.

Are there any formulas & such to come up with a wholesale purchase price. The lot is in a great neighborhood & there is actually a house being built next to it.

Thanks in advance.