I haven't tried this (yet), but I read that pointing out how much more cheaply one could get a timeshare on eBay gets you an immediate out from the negotiation process.

Timeshares on eBay are crazy cheap by comparison. A timeshare in Hawaii during prime season can be had for $50k or something like that, which sounds like a lot until you realize that the vacation clubs will sell that timeshare for, like, $500k.