Seller Financing -- In Need of Creative Advice

[Matt Speer]

Situation: 
Imagine a property in Fishers, IN (recently awarded safest place to live in US), a suburb of Indianapolis, IN that is surveyed as 3 lots and has two properties on the lot. One property is about 2,200 sq. feet and has a 3 bed/2 bath on the top floor and a MASSIVE "4-car garage" on the bottom --I'd put some money into it and make it a duplex with a studio. The other house is a 2 bed/1 bath that has been well maintained. 

The current landlord is 70+ and has been renting the property since he built it over 30 years ago. He rents the top of the "duplex" for $1000/mo and the 2 bed/1 bath for $800/mo. The previous tenant for the $1000/mo had been there for 16 years before recently leaving. 

I spoke with him and he mentioned that he would be open to seller financing of the property. He mentioned wanting $25k down and wants a ballon payment after 5 years (remember he's old and wants money relatively soon). He mentioned "4-5%" interest which I thought was low. 

My Take: 
He mentioned wanting at least $300k for the properties. I work in the office building that was recently built that is a 30 second walk from the house. The area is BOOMING. There's so much construction that it's hard to even get in a routine as you drive to work. I know you're not supposed to plan on appreciation but I believe that this property could have some serious upside with appreciation. If I could cash flow a several hundred a month and wait for this appreciation I believe it could be a gold mine. It also has a lot of potential to market to developers/commercial investors due to it's location. 

QUESTION: 
Does anyone see an opportunity here? Is there an ability to get creative with financing in order to take advantage of the owner's unique situation?