I am also looking for multifamily, but more in the 40-100 unit range. 

Real estate secured loans, for instance are in the 7-8% range. 

That being said, it wactually ranged between 6'-5" - 6'-10".

If your just looking to start slow and have 10-15k or even 5k id say just try and land a deal in that price range.

I am not bound by usury laws in California.  

Quote from @Jason Hoekstra: I just finished a 1 bedroom build 866 sq ft in Chalet Village on a one acre lot with long range views.  

I'm going to offer up a few words of caution, as well as the way I like to approach flips.... but to answer your up front question on financing, the typical heloc is going in the 9% range.  

More than likely, it would end up being a house hack somewhere in the 300-375k range.

Aren't loans like this usually in the 10-12% range?

When I started managing single family homes, lease up fees were the other main fee that investors focused on and the fees ranged from 50%-100% of the first month’s rent.