Make sure you fully understand the mechanics, fees (explicit and hidden), and your P&L impact after financing.

A systematic inspection could uncover some hidden problems and assist you in your buying decision. 

I'm not trying to rip off the owner or do anything unethical, I just want to use possession of the tax lien certificate as a foot in the door to seize control and save this gem of a farm before it completely goes under.

He said he would get me a rough estimate in a couple days.Then a few hours later, presumably after he started realizing the value/profit that was hidden in this house, he text me and asked if I would be interested in selling it to his company.

Mitch Kronowit your not as hidden as you may think.

Sometimes that price is hidden so no one know for how much the lender will let it go.Fine print is buyer beware, any other liens like taxes or municipal lien, building or code violations stay with the property and it will be buyers responsibility. 

Or is there some hidden purpose for this disparate pricing?

After that little gem slipped out of her mouth, she shut up.

I'd thought I'd done a good inspection but the real problems were hidden in a fake ceiling where one leak was and around windows and a sliding door that had been installed without any protection from the rain. 

Perhaps you could structure a seller finance deal, then sell some of them off and keep the gems?