@Brian Flint If you want to live there and you don't mind that you're paying full ARV, then it could be fine. Personally I would only move into it myself if the seller agreed to lease it to me for his payments and gave me at least 5 years to buy. I wouldn't want to have to mess around with getting financing or force my family out of a lovely sounding home after just a year or 2.
Whether he's going to go for that remains to be seen. It doesn't sound like he's particularly motivated, otherwise he'd be talking more like: "Just take over my payments, please!"
@Doug Pretorius Yes that makes much more sense thank you.
You don't mention any pain that they seller has. Depending on their situation, there are a million ways you could structure a deal. Why on earth would they sell at a discount if they don't have to? What's driving them?