We really want to avoid borrowing against any retirement investments.

If you are close to your goal or lets say retirement, a bunch of free and clear properties to support your lifestyle is a great option.

She kept my checkbook and signed checks until she retired. 

Bring up what their retirement plans are.

That being said I estimate there is about 30-50k worth of work to bring it up to the level of the comps in the area.My wife and I are not rich but we have no debt, we have 250K in our retirement, I have a pension I am vested in and we have about money tied up in investments that we can if need be make liquid.I have been working with a mortgage broker friend and he says we are golden to purchase anytime but I don't want to go the traditional route with 20% cash and here is the strategy question.  

Right now my retirement fund is producing 12%. its 10 year average is only 6%   I would look at some other investment that doesn't require so much expense to get in and out of before I bought this house.  

Have official loan documents drawn up professionally so they could potentially sell the note if they need the money suddenly.This may not apply, but if the money is coming from a retirement account you might run into some trouble since you're family.

Seriously.I want my "retirement" income to be $50,000 a month or $600,000 a year, a pretty reasonable goal.

I'm assuming that they have reached retirement and are content to sell and relax.

My goal is to find a full service CPA who can advise me on retirement investments, tax write-offs, and company structure as far as LLC, S-Corp, C-Corp.