Are you talking about Lake Buena Vista Resort Village and Spa? The one with the big pirate ship in the pool?
If so, I got the best rate by booking through Chase "Ultimate Rewards" using my Chase credit card. You can pay with points or cash (if you have a Chase card). Alternately, try calling the resort directly. When I did that, they offerred me rate very similar to the lowest rates I was seeing online.
But, I didn't not look at all into renting through owners.