At any point, he could pay off a portion or all of his loan, which would have no bearing on your obligation to him.Wraps do trigger the due on sale clause, and that's a risk of the new buyer that should be disclosed.

Each time a parking spot or garage spot becomes vacant, I will test the market a bit to see what the market will bear. 

It has no bearing whatsoever on any title search or how much time you have.

Please bear with me here.

A little off-topic but the most interesting legal description I ever came across working in the title industry was a metes-and-bounds description (not platted/subdivided) that included a call-out along the lines of "...then east to the big tree where Billy Bob killed a bear...."

Bear in mind he invests in south city, blue collar neighborhoods. 

Bearing that in mind I am going to play devil's advocate here.

I am not sure that has any meaning or bearing on an investor's success!

In others, deposits must be held in an interest bearing account and the deposit+interest refunded as appropriate. 

Certainly there are people who get emotional about the property they are selling but a sellers response to an offer has little bearing on whether the offer was fair or not.