The reason why the rental price for points is $10-$11 is because that is how much most people ask. Most people just want to get rid of extra points and they consider anything over their dues costs "gravy". I asked (and got) $12 per point on both of my last rental transactions.
Are you trying to determine the true cost of your points on a yearly basis? That's a pretty hotly debated issue here and the answer depends on what your assumptions are. FWIW, I know very little about finance (and I suspect it shows, LOL!).
Here are some questions to ask yourself:
How much did you pay for your points?
Did you finance? If so, then you need to include the interest in your calculations.
What about dues increases? Look here for a Dues History:
http://personalpages.tds.net/~rb/DIS/DVC/DVCDuesHistory.htm I know that I am paying a $1 more per point for my BWV points than when I bought them 6 years ago.
What about inflation? Time value of money? What if you invested you purchase price instead?
Here is a quick and dirty calculation ...
If you ignore everything except for initial purchase price of 100 points at SSR in 2008: $10,400
Dues: $3.80 per point for a cost of $380 the first year with a 3.4% yearly increase in dues (average increase for OKW over life of
DVC).
I get a total cost for 37 years to be $37,732 or $1019 per year or $10.20 per point.