The current version of MB allows sell-back of 100% of the 1st year's points. (I think the max is still $2000.)
I suspect that there is no true supply of BWV points (or OKW either), but this may have been a case where someone forfeited their contract by non-payment and DVC reclaimed the points. (Yes, it does happen.) Forfeiture of timeshare contracts is common in the industry and can result in some real resale deals- some right from the owner's association itself (That's unlikely to occur with DVC).
I would also doubt that DVC has much opportunity to exercise their "right-of-refusal" as resale brokers are pretty savvy in advising both sellers and buyers what level of offer is acceptable to DVC...and that DVC will allow a buyer to raise an offer if it is too low.
Letting your guide know you are interested in an add-on at BWV or OKW can't hurt, but is not likely to be a fast way to get some more points.
Good Luck!