I was told Disney lets contract go if they dont have any current members waiting for the points with that use year, and if they wont loose any money on the deal. This is why sometimes you will see a good deal get by while other times they scoop up something high.
A broker just broke it down for me like this, recently. She hasnt seen anything for less than $65 for HH; 69 for OKW; and 70-72 for the others get past Disney, lately.