If you indeed find a good deal, an you use an LLC as the holding structure, you can also assign a higher percentage of the profit side of your K-1 ... or define a preferred distribution for that member that would equate to 10%.

Does anyone know of a cheap answering service that would do (what equates to) data entry while taking calls from sellers?

Break it all down, and it equates to an 11% interest rate on that "2nd mortgage portion" of the loan above 80%.

So you're collectively equating each of their 90 additional hours to your $7K down payment.Does that seem fair?

In a purchase that's loosely equated to cap rate. 

Downturn doesn't always equate to more tenants.

@Nikki Grizzle  yes as stated by @Kim Younkin  above your the one who is totally naïve in this equation.  90% of relators sell homes to home owners to live in. 

For land, use assessed value and APN scheme to create an equation to price each property individually.

FICO scores are part of the equation...

Lots more math to do on this equation, but you have identified a potential opportunity which is a great start !!