Buying first home from Family- Needs Reno

[Eric Frey]

I have the opportunity to buy my father's house. Currently it is vacant (several years) and in pretty rough shape. I have several questions that all seem to open fields of further questions, and I'm not really sure where to start. I'm hoping this post will kickstart that.

Firstly, we haven't settled on a price yet, but my dad has expressed that he will make me a very good price. So my question here is- can someone sell a house for any price, even if the house is potentially worth more? Sub question- what are the tax implications for this if so? Example numbers- Let's say I purchase for 10k, and the house is worth 50k in its current condition.

Second, this sort of ties into the first question, but does the house need to be appraised? I'm hoping to not go through an agent to buy it, but who Should I talk to? A real estate lawyer? 

Third, I plan on buying the house for cash, but I will not be able to cashflow the renovation. Where do I find the money to do the mixup work?

Some info about me- I am a home inspector and before that I worked on houses, so I know quite a bit about what needs to be done and (roughly) what it would cost- and I'm planning to do a lot of the work myself.

I really appreciate any advice y'all have. I can go into more details about the specifics of the home, I was just trying to get some ballpark questions answered first.

Thanks,

E