Ask your CPA, title officer, closing attorney, doctor, dentist,  or another trusted professional for a recommendation. 

One office space is rented by a dentist for $3600 per month (1.5 years left on lease and when I met him he indicated he is staying), the residential space is renting for $2700 per month (current tenant has been there for more than 20 years already) and there is a third office on the ground floor that is currently vacant (the owner has never really marketed it, but it seems to me to be another $2500-$3000 in gross rent).

I have a few dentist friends and nurse anesthetist buddies.

It could be your dentist, your doctor, the professional football player next door, they can provide 100% of the money and are easier to please.

Doctors, Dentists, Business people, friends, family, etc.

Generally, they'll give the physicians (doctors/dentists) 0% down on primary residences and 10% down on second homes (which we just happen to decide to convert into an investment the day after closing).

And it may be a lot less or a lot more depending on the investor.If, like myself, you have a spouse and kids, and you need to honor your spouse's risk tolerance, meaning, you can't just quit your job until you've replaced your salary, then that is the large goal in your horizon.If you are a dentist, you may need to make $300K/yr in RE to consider becoming a full time investor.  

It could be your parents, your barber, your next door neighbor, the clerk at the grocery store, your accountant, dentist and so on.

Well, just got back from the dentist, so I'm under the influence, but still;1.

Just keep in mind that you will probably still want to insulate whether they pay anything or not - so don't lose face asking and them saying no.I had a pipe burst last year - stunk to be me - paying a plumber is like paying a dentist - painful but has to be done.