Like any real estate transaction, if you are buying resale, you can offer the seller any amount (ie: "talk them down" from their asking price.) However, where DVC differs is that Disney gets ROFR. So, even if you talk the seller into a GREAT price, if Disney decides that it is "too good of a deal," they will exericse ROFR and you don't get the contract.
The friends and family promotion going on right now (at $86 per point) is considered a good deal. If you want a smaller contract (less than 150) or if you want to try and beat $86, go to The TimeShare Store and view the listings there.
Bottom line: there is not a lot of wiggle room when it comes to buying DVC. Where you can negotiate is things like who pays closing costs, MFs, etc. (for resales).