Owner auctioning his home?

[Steve Foth]

I saw a sign while driving that said "owner moving, make an offer." I naturally stopped by and talked with the owner who is elderly and disabled. He told me he purchased it for 25k about 5 years ago in the hopes of fixing it up, but his health has prevented him from doing anything to it. He said he will be auctioning it himself, so he is basically selling to whomever offers the most that day. He owes $1400 in delinquent property tax and said it is otherwise unencumbered.

He printed out a 1 page bid sheet and wants $500 upon winning and the rest within 24 hours, then he will produce a quit-claim deed.

The owner also mentioned that only 4 people had inquired.

It needs a lot of work, so I am planning on a walk through with my contractor this week. At first glance, I cannot see it being worth more than 5-10k due to the area and rehab. ARV approx 40k, assessed at 54k which is pretty average for this part of Wisconsin. This will be a hold, I know it would not be worth flipping. It is a duplex, but looks like he was converting to sfh. It is a lot more work than I really wanted for my first, but that would make it a hell of a lot more educational and scare off much of the competition.

What should I look out for that may be different from all the foreclosure auction threads I have read? I worry about the title being clear and my limited ability to estimate rehab costs. This would also be my first, so I may just be over thinking this.

I appreciate all feedback--even if it ends up being a lashing :)