If it would fetch another $10-15K a year in rents, what would it be worth paying to do the addition? 

Throw in low offers and some people will be motivated to sell due to life circumstances.

I offer this exact deal in my markets. 

This is a core deal, which certainly offers some risk mitigation, as they allude to.  

I'm going to sell one of my rental properties and offer seller financing with a 30-year mortgage term.

Hey all, this post is for anyone with some open weekdays who is also looking for better/updated photography for their short term rental (also some bonus tips on partner cross-marketing).Partner with influencers (find them on FB and Instagram or I can help you find a few) by offering them a stay during the quieter mid-week time in exchange for professional content and posts from them.

Adding additional assets, a familiar market, buying a house "for free" as I call it, and gaining experience with lower level of risk How did you find this deal and how did you negotiate it?

So I thank you for all your input, and I look forward to any additional information regarding this.   

Numbers are a little tight so I'm hoping to get an offer soon.

$300K should allow you to buy a duplex/2-unit and both doors should be offering a profit even at 15% down.If you are in a situation where you are getting hit with high taxes, high rate, low rents it might be a "Walk away deal".I have to have conversations daily talking people out of buying a particular home because its a bad deal.