Purchase by land trust listed as a deed correction, not as a sale

[Kay March]

I'm looking at a possible fix and flip. The former owners defaulted on a private mortgage. Foreclosure proceedings were halted when the property was purchased by a land trust which paid off the mortgage. Now the land trust is trying to sell the property for $170,000, but before the land trust purchased the property, the outstanding debt plus charges only came to about $50,000. I don't see a way to find out what the land trust paid for the property. The transfer is not listed in the property records as a sale but rather as a deed correction with a $100 "price," so the transaction doesn't appear in, for example, Zillow's price A history of the property. Is there a way to estimate the price paid by the land trust, given the known outstanding debt? Is there a formula that is typical for this kind of situation?