Investors & landlords

It sounds like you're handling the K-1 properly.  On the purchase price, your own records are what you should use.  The partnership is simply reporting what someone else told them, so if its mistaken they'll correct it with whatever number you want to provide (not that you need to correct it).  So you'd use your purchase price, and the K-1 Sales Schedule col 5 ("Cumul adj to basis") to work out your correct cost basis.