Sellers underwater. What would you do?

[Samson Kay]

I was recently approached by a motivated seller that's is currently upside on his mortgage. It's a condo that currently is worth 70k, and he owes 90k. Between condo fees and the existing mortgage, operating expenses end up being around 950 per month. I believe that we could get 1200 per month in rent so we would Cashflow about 250 a month. He basically told me he would sell the place for what he owes. He has no interest in becoming a landlord himself. I was thinking this could be a good sub-2 candidate. Would you take this deal? How can I sell the idea of " subject to" to this seller?