Technically, BLT isn't sold out yet! I had a good friend just buy in there, and was given ALL of the currently offered incentives.
SO, while they may not longer be actively marketing BLT - there are still direct contracts/points available there.
We tried to buy points at HHI through Disney, but they pretty much told us we would have better luck on the resale market - being that this was before the resale changes....we took their advice and got one of the best DVC deals I have ever seen.... anywhere! Less than $42.00 per point - and the contract was completely front loaded with 95% of points current, and banked.
I really didn't think it would pass ROFR, but it did! Thanks for the advice, DVC! HAHA They were selling HHI for $85.00 p/p I think at that time.
BUT, OP - on your question - I don't think they raise the prices for resales at sold out resorts - the contract length is shorter, so you have a shorter usage period.