Example: I borrow $10,000 at 10% and pay back $11,000 after six months.

I just don't think your example is that realistic at all.

For example, you set up key word alerts. http://www.biggerpockets.com/alerts

For example, you set up key word alerts. http://www.biggerpockets.com/alerts

Example: Rent includes $150/quarter in water, if they go over that amount you present them with a copy of the bill and have you "settle up".Or you can pay it and just have them reimburse you the full amount every quarter. 

For example, you set up key word alerts. http://www.biggerpockets.com/alerts

For example, you set up key word alerts. http://www.biggerpockets.com/alerts

However, a $100,000 purchase in the 1980's in California that sells for $2 million today or a $35,000 condo purchase that wold cost $639,000 today - neither example is an applicable experience for an investor starting out today to try and model. 

For example, you set up key word alerts. http://www.biggerpockets.com/alerts

For example, you set up key word alerts. http://www.biggerpockets.com/alerts