Private money sources abound and are often easily negotiable to a win - win position for both borrower and lender. 

Then when you have the capital built up, find some private money and do a break even deal with them (hold it til they make back their capital investment, or flip it and split after recoup.) 

First thing you should be looking for is a private lender!!  

In my view, a wise short-term use of your money would be private/hard money loans, with 6 month terms, to residential flippers local to your area.

That's how we found our portfolio lender, our hard money lender, our private money lender, and a bank that would give us a line of credit.If you are looking to go conventional you are going to be looking at 25% down.

I am thinking about privately lending to a friend who has many years of successful REI experience.

Started by finding private investors so no money!

...is a private money lender to help fund my rental portfolio. 

Private Lenders

So long as you are not pledging a personal guarantee - and thereby providing the lender additional recourse in the event of a default by pledging your personal assets as security for the IRA's debt - then the source of the loan does not matter.Most private lending transactions, especially owner-financed notes, are non-recourse in nature.