Seller owes $350k on the property (Not a foreclosure)

[Praise Emmanuel]

I am trying to buy a property to flip, it’s vacant, and the seller is trying to sell it for $350k because they have a mortgage for $350k. The problem is that the house is definitely not worth $350k, and the seller says they are not in foreclosure. I would have to buy the deal for $250k for it to work. How can I structure this deal with the seller ?