Mailing yellow post cards to cash buyers using a list from list source, post a "ghost ad" on Craigslist.

Or are they financing using traditional products and financing the renovation out of pocket?

Both of these examples are generally relegated to the well heeled homeowner due to the costs and individualized nature of the final product.

I have a full time job that I love as a product design engineer and I want to fulfill my other dreams which is owning my first Multifamily home.

Be the first one to make decent mortgage origination software, make a boat load of money because you've got a monopoly product. 

My two cents is that if you had a good experience with any professional by all means pass on their name (it's buyer beware -- people asking for referrals should know that it can go either way in starting a relationship with a referred professional), unless you know of something that's causing the professional's work product to slide.

there are extra buyer premiums they add as well, let alone the previous mentioned ghost bidding. 

I have a full time job working for an Engineered Wood Products Company as a Safety Manager.

One pays the premium for the end product but its way more passive to fully passive.

I see you have been doing some research with a Turn-Key product.