If I am reading correctly the value  of the home is 425K.

From what I have read above nothing about this sounds like a great deal, offer him what you think it is worth to you and instead of fretting about it keep looking for a great deal.

I read nearly 50 business and real estate investing books throughout high school.

I was reading an article written in earlier 2000s.

Maybe they are viable with higher-grade properties with larger margins.Also look too Twin Oaks Really.Fellow Investors when you are reading information on these forums make sure you verify the source of the information you are reading when you're digesting all of it. 

The best advice I can give is to read/listed to everything you can and don't be afraid to ask questions and network with anyone you can who can help you advance and meet your goals.

Please click on the links, give them a read, and share your thoughts in the comments.First is a post that I feel will help not get overwhelmed with the amount of info that is here on BP:https://www.biggerpockets.com/blogs/5868/52761-the-simple-guide-to-getting-started-on-bp The second is a post that will help get you focused with your real estate investing goals:https://www.biggerpockets.com/blogs/5868/52743-im-new-to-bp-any-advice-would-be-appriciatedThe last one is a post that will help you choose an “investor friendly” real estate agent.

Since now I have been reading the rules, paint has a self-life of 3-5 years and unless I have damaged the walls, I am not responsible for it.

If I'm reading it correctly, it documents four falls by three people.

First off, he has been a paying tenant for a number of years.... in the many stories I have read on BP, it seems there is plenty of cost every time you turn over a property, so if this tenant has been in place for so many years, you will have turnover costs anyway, but you have saved a ton not having them for all these years, so for the folks tearing your business practice apart, I'd say it has worked out thus far.In regard to what to do...