OP, take a look at the Rent/Trade board. You'll see a whole range of prices there, from $12/pp to about $6/pp. I would guess that the people renting for $6 are coming to the end of their use year, so they've got to get rid of the points quickly or risk losing them. We call 'em "distressed points" That's why they're willing to take so much less.
On the other hand, people who are renting for the top price per point are probably not under any pressure to rent the points quickly, so they're not very likely to be receptive to bargaining. The last time I rented my points out, someone tried to negotiate the price.....but I had 15 other PMs from people who were willing to pay my full price, so I politely turned her down.
What I would suggest is that you find a price range that would be acceptable to you, and look for owners who are advertising in that price range. I think that will work out a lot better than trying to negotiate price with an owner.
If you were thinking of renting through a broker, check out
Dvc By Request. They have last minute specials, with reduced prices, for those distressed points I mentioned earlier.