My estimation was with leverage I could do about 7 homes a year and each year after it would increase. 

We all know 'housing affordability' is one of the hottest political topics as of late but I'm not seeing any commitments to increase inventory. 

Higher assets or cash in the bank increases what is called you compensating factors which banks/lenders use to qualify.

You are already paying rent, so pay it to yourself to increase cash flow and accelerate savings for the next investment. 

That sounds like a lot of work and I'm sure he would prefer to avoid that work and just sell it for $1.9m or $2.0m.if I were to buy it from him, to get to cash flow neutral I would need to increase rent on all 6 units to market rates and my monthly payment would need to be close to $6.2k/month, which would be $100k down payment, $1.7m loan with seller financing at 2% interest rate and flexible ballon payment.What would you do if you were me? 

You would have to be significantly cheaper than my current cleaners for me to give you a shot, because I generally have only changed cleaners for either consistent subpar work or increasing/unreasonable prices.

The mortgage would stay under the seller's name.The buyer could then rent out the unit, renovate, etc. to increase cash flow or make more money.But aside from a possible "due on clause" being called by the mortgage company, what's the benefit to the seller?

Purchase price: $169,000 Cash invested: $33,800 Property was recently renovated to increase the value of the property and the cashflow What made you interested in investing in this type of deal?

You could consider the areas in the city with the highest value increases.

Quote from @Basit Siddiqi: I personally would not buy real estate with a retirement account.There are just too many headaches that are not worth the potential increased return.Some headaches when it comes to investing in real estate with a retirement account1) LTV values are less and harder to find lenders.2) Potential to sell or partially distibute the property if you have to do a RMD(Required Minimum Distribution)3) If you run out of cash and have to make a major repair, you may be out of luck and have to sell.4) Having to potentially worry about UBTI(Unrelated Business Taxable Income)I would personally invest in stocks/bonds/notes with a retirement account.I buy deals with cash and use a ROTH SDIRA so there are no RMD's.I buy at huge discounts to retail.