There are probably 2 appropriate answers:
1. Supply and demand. BCV is one of the smallest (and newest) resorts and its popularity with guests usually pushes resale prices into the $90s. BWV, VWL and SSR are usually in the mid-80s. SSR has the longer contract, but the other two are smaller and thus there are fewer points available. Finally you've got OKW, Vero and HHI selling in the $70s. Two are off-site resorts.
2. The second (and perhaps most influential) reason for any resale prices is "because that's where
DVC wants the prices to be." DVC has Right of First Refusal on all resale transactions. As such, resale prices tend to settle a couple dollars higher than what DVC is typically spending to buy back the points. In other words, if history has shown that DVC will buy-back any resale offer on SSR points of roughly $82 per point, prices will run around $84-85 since buyers actually WANT to get the contract. When DVC starts paying more per point for a given resort, brokers and sellers will catch on quickly and adjust their pricing accordingly.
DVC points can be used at any resort for reservations inside of 7 months from the check-out date. However, you can book at your Home resort (the resort where you actually own the points) 11 to 8 months ahead of check-out.
If you buy points at a resort you don't intend to use, you'll always be trying to book on 7 months' notice or less. Sometimes that will work. Other times it will not. In my opinion, if you plan to use points at a Walt Disney World-based location, it makes sense to own points somewhere at WDW. That gives you the ability to confidently book a room as much as 11 months out, and then attempt to change to another resort at 7 months.
On a side note do you think Disney made a mistake in building saratoga?
Despite what some would have you believe, there are many people who adore SSR. Those who don't like it still have a 4-month booking priority at their choice of Home resort.
If all of the DVC resorts were carbon copies of one another, there wouldn't be much variety. As it is we've got 7 (soon to be 8) distinct destinations to choose from. Sounds like a good concept to me!!!