They are in a market where you have a very limited amount sellers you have to be able to compute multiple factors per transaction and you have to spend money on marketing. 

The "Secret" is to market enough so that you have multiple buyers to choose from-and you are "desperate" and have to "SETTLE" for the only responder!

I organized a viewing of both duplexes next day where the realtor informed me that it was a very competitive scene with multiple cash offers already placed.

You can also get real estate transaction info for free from your city and county and then look for individuals and LLC or corporations buying multiple properties for cash.

I know in my market getting conventional or FHA financing on a property with multiple residential buildings on it can be tough because a lot of banks consider is non confirming or essentially there are little to no comps to use as a comparison. 

Other option is if you have another property that is higher value, you can borrow against other real estate or multiple units to increase the loan amount For small loans you better off finding private person who will be interested in lending small amount.

She would be comfortable investing about 350-400K into acquiring multiple properties to generate needed cashflow.

Usually what happens, (I haven’t invested in real estate yet but I have seen this happen multiple times with friends I used to associate with.) is when you start that eviction process, you’re stressing them that they have a responsibility they need to focus on.

30 years of 3% annual growth equals to 2.43x multiple.

It would depend on multiple factors.