Owner-financing purchase...but could be a tax foreclosure?!

[MaryThom Newcomb]

Brand new to real estate but am loving it!

While driving for $$, I found a house in disrepair. In my research, the elderly gentleman that lives there owns it outright, but has NOT paid his taxes in years. (Just a matter of time before it ends up on the county's tax foreclosure website)

I've knocked on his door, (he didn't answer), although his neighbors say he does indeed leave the house and he IS friendly. 

What's the best way to 'entice' this man into selling his house to me? It needs a total rehab but it's in a fantastic rental area. I highly doubt he will want to move....

Thank y'all for your help in advance!

MaryThom