I have a property I am interested in bidding at auction and need help figuring out a max bid. this will be my first auction purchase. I have some experience working for my dad as he has around 30-40 cheap rentals, but he hasn't made a purchase since 2009. Markets change, and what was accurate in 2009 isn't today. I researched the deeds of trust and know the guy losing the property paid $99k in 2004. Zillow says it is worth $139k, tax rolls have it at $103k. From looking up deads of trust in the area borrowed amounts all over the map in last couple years, anywhere from $125k to $260k for similarly sized houses (obviously quality may be different). My best guess would be to that this house could sell around $179k in good condition. What would be a good way to determine a max bid for this potential flip? It is a  1500 sq ft 3/1 that will need central A/C added and possibly convert some space to make it a 3/2 in order to get a good retail price. House looks straight from the outside, but no idea anything else on the inside obviously.

I tried approaching the owner to purchase the house pre trustee sale as this is not his homestead, but he didn't even open his door (told me not interested through the door) and was completely closed to even speaking to me about the house. 

Also I know the owner has like $200k in IRS liens...what kind of research do I need to do about that, or does that disqualify the property.