My partner and I have begun using e-commerce (Ebay, amazon, IG, and soon Etsy) and Uber as sources for extra income.

Find out the replacement dates on those bigger items:Roof will last for the anticipated life expectancy unless damaged by outside source such as a tree limb.  

My fear was that investors would be proprietary and secretive about their funding sources and private lenders.

I have read/heard differing opinions that wholesaling is a good place for someone new to start and other sources say that it is not a good place to start for a beginner.

I have purchased flips from wholesalers as well as sourcing them myself. 

They can be an awesome and often overlooked deal source as well.  

I'm using the scenario where you have another business or a source of income that generates more than enough cash to invest in rental property)@Jim Shepard - does this mean you typically take 15 year loans (or shorter) since you have another business that generates income?

@Gregg Pauly- You have to call people (brokers and deal sources) to get financials.  

I'd encourage you to meet other BP-ers here in Tokyo, like @Bill Baldwin and others, who have been super helpful and really an invaluable source of information and advice.  

Non-national banks are the best source for portfolio loans.