I'd almsot say look into a NEW minivan...with the rise of popularity of SVU's and cooler cars, people have lost interest in the minivan. Lately car dealers haven't been showing minivans in their ads for whatever reason either yet on the lot the salesguys are given incentives for moving them off the lot at ANY price. At my local dodge dealer for labor day weekend they will have a promo where salespeople will get quad points for every minivan they sell, and they will also be discounting 2005 models, so getting a minivan in the 8K-9K price range won't be too hard.
As for haggling, find a black guy, yeah i know it may sound racist, but white used car salespeople are assholes, black used car salesmen, well, they are awesome and they seem to be able to barter back and forth a lot more than their white counterparts. The last black guy i delt with got me 2K under KBB on a used car /w warrenty, thats friggin amazing at a dealer (this was at a ford dealership). A white guy, not a block away, on a very similar car with LESS options, wouldn't even break 500 under.