I just want to make sure I'm not getting myself in a situation that will be a headache as far as inheriting a tenet who I cannot remove. 

Draft your contract properly to begin with and lessen the chance of having to litigate. 

What does your buy box look and what are your overall goals with your inheritance?

If you are this close to the border or cost you need to purchase through a corporation or through a bank trust (Fideicomiso - Think of this trust to be similar to an inheritance trust or a living family trust in the US.)At all times you are the legal owner of the property, the best way to see it is as a permit or license that allows you to purchase, use, enjoy, rent, renovate, inherit, etc. a property in this zone.

When you are inheriting tenants, you have no idea what kind of background check was done on them.

New York, for example, just arrested a woman for changing the locks on a squatter in the $1 million home she inherited.

Good advice by @Eric GerakosAssuming for a second it’s worth doing, remind him his broker price of 500 will be lessened by the 40k commission, and the bank will be making the money off the loan, not him.So try for 460-480 with as low a down payment as he can stomach and offer to split that payment into upfront and 3-6 months later.

Many properties had owners who passed away and the estate taxes on the inheritance of the property was never paid.

The point here is, because I thought my bid would only go toward 2007-2008 (and not subsequent years), I calculated my maximum bid way too low.I'd been trying to contact the owners (out of state, inherited the house, in financial difficulty themselves) in vain since September 2014, so I am almost 100% sure that they will not redeem the tax lien, or even know it's been sold. 

My sister is looking to unload our childhood home that she inherited 7 years ago.