Prices and terms are set between you and an individual.
DVC members use "points" to "pay" for the villas. It's become the custom on this board to charge "per point" for the reservation. Generally, $10 is the lowest you will find (unless someone is desperate to unload expiring points).
Like WDW resorts, the villas "cost" different amounts at different times of the year. However, DVC seasons are different than WDW resort seasons. Also, DVC members pay quite a bit more to book Friday and Saturday nights. The amount of weekend nights can make the difference between a Disney deal and a rental less signficant. However, sometimes a person will give you a reduced "per point" rate for the weekend. (This is why I think it would actually be better to just price a vacation rather than concerning a non-member with worrying about points.)
Renting from a member means you are treated as a member and will get limited housekeeping. If you want daily maid service, you have to pay for it. If you rent from Disney it's just like staying at any other Disney resort.
Also, because it's an agreement between individuals, you have to establish trust and lay out the cancellation policy. Generally, it's a non-refundable transaction although most members will try to reschedule if you have to cancel. However, a member has restrictions too and can't guarantee they can get future dates for you.
You might want to get the best price from Disney and book it. You could then explore renting and compare the pricing. If it makes sense to you, cancel the Disney reservation and go with the rental.
You can find a DVC points calculator at the top of this page. I think the 2005 points are still estimates. We can also try to give you an idea of the number of points you'd need if you want to share resort choice and time of year.
Good luck planning.
