Seller finance deal analysis advice

[Armin Rostami]

Hi everyone, apologies if I’m missing any points here but I am a newbie and looking to get in my first investment property. I came across a seller finance deal here in San Diego and just trying to make sense of the deal and hear some thoughts and advice on how the experts go about thinking about this. Would love to hear anyone's thoughts on what counteroffer you may have for the seller if the deal is worth pursuing at all and how you guys run the numbers and analyze the deal. Thank you again!

Here is the info:

La Mesa, CA

- 4bed/3bath, 2204 sqft, built in 1904, B class location, Property needs TLC and some renovations but still rentable with the current condition. Seller lived in the house their whole life.

- Main house: 3bed/2bath home. He says should get 3500+ in rent. - Granny flat: 1bed/1bath. 1900+ in rent 

- Purchase Price $900k

Owner would like a down payment of $225,000.

She can carry the rest at 6% interest only for 5 years.

She'd also like to prepay/ discount the purchase by $90,000 for up to 5 years of rent for the granny flat. That comes to $1500 a month. The 5 years can be less.