Need help negotiating purchase of currently rented home

[Hilda Conrad]

I have been living in a rental home for ten years... yes, ten years of wasted $. I have maintained the home myself without much involvement from the owners, probably why they have never raised my rent ($1400), which is also way under market for this area and size of home. The home now is in need of some big ticket maintenance items like roof, fencing, and deck. It is a very nice home but dated and could also use some updating aside from the interior painting I've already done. I would like to purchase the home from the owners but am unsure how to approach it in a way that is appealing to them. I don't know how to go about negotiating a fair deal for us both. Also need feedback regarding seller financing versus 203 FHA loan that will allow for extra $ to make the repairs and updates. Thanks for your input!