Pretty much everything is negotiable with a resale contract. The major exception is the number of points - no one but Disney can "break up" a contract into several smaller contracts.
In addition to the price per point, many here report that they have negotiated who pays annual dues for the year in whcih the contract changes hands. Closing fees are also often negotiated, although the buyer usually pays those, just as the seller usually pays the broker's commission.
Make what you consider a reasonable offer and see what happens. Sometimes the seller will just say no , sometimes he/she will make a counter offer and sometimes your offer will be accepted. Keep in mind that Disney does have ROFR and if the deal is "too good", you may lose it to Disney. Sellers probably doesn't care who buys it if they get what they wanted out of the sale.
Good luck!