In many of these financings, the buyer paid a purchase price based at least partially on the increased cash flow generated by the property being “proven” as a successful STR.  

figuring that if I track and work towards creating and "presenting" 250 specific deals to my clients.My Theory being: Tracking "deals presented" will pull forward the need to go search and find deals, and will also drive the deals closed and revenue numbers, so we shall see but logics out to me so I'm liking it so far.

That said it is possible that you need to evaluate your stays and decide if it is worth taking shorter stays or sticking to some longer stays to reduce your time commitment and maximize the revenue for time invested.

I was interested in something like owning a rental property as a way to generate some additional income. 

Even if it does, there's closing costs to consider.As I said, I have no cash myself, so I'm asking how I can deal with generating cash for closing costs (and a down payment) if it comes to it.The house costs $139000.

I’ve used PriceLabs Revenue Estimator in the past with great success.

UBIT is generated two ways.

Revenue stream.  

If so I feel like you should be doing fine on revenue.

The property will need to have a slight rehab to get it up to STR standards, but when complete it should easily be a $200k Gross booking revenue property.