$15 per point for up to 24 in a Use Year from Disney, but you can only purchase to make a reservation at 7 month window or less.
You can Transfer either points into your account or out of your account (but not both) one time each Use Year. If you are transferring points in those points are under your 'control' ie, you call MS to make the reservation you want with those points. Just remember that the points transferred in keep their original Home Resort designation & Use Year, so if you're looking to combine them with your HR points to book between 11 month thru 7mos+1day window then you'd need to find a member with same Home Resort that you have.
Renting from an owner means that owner books reservation for you, sets up Magical Express, Dining Plan if you want that and makes any requests / changes to the reservation and controls the reservation until you check in
( that member can also cancel the reservation too ) and that owner decides what their cancellation/refund policy
if any at all will be should you find that you can't make the trip for some reason. You cannot do anything regarding a rented reservation, not even calling MS to ask something about it because they will not discuss it with you, they will only discuss it with
DVC owner who booked it.
Good luck