My interest in real estate is to continue to acquire wealth through SFR home flipping and eventually build up a personal portfolio of income producing properties.

My ultimate goal is to build up a large portfolio multi-unit properties and vacation rentals.  

Secondly, I really would just like to build up decent cash reserves before stepping into some buy and holds.

This makes it a single lot which would meet the frontage and setback requirements, but would allow him to also build up to the full 20 units/ac.That triggers the next question what is the valuation difference between his fee simple townhouses/duplex and a "condo"?

I am almost out of reserve as the lender requires 6 month for PITI for all the rentals.How to build up the reserve?

My strategy is to buy multi units and hold them as rentals to build up my cashflows.

Despite the historical natural of the properties, I think the properties there provide the ideal combination of cash flow and equity build up when comparing those in Fontana, Riverside, or Rialto...etc.

The listing agents usually know private investors and let them know first, before the ink on the listing agreement dries.

The rest you can build up with their referrals. 

I am trying to build up investment capital of 250k.