I would to go www.kbb.com , you can compare mini vans, see which ones have the best safety options, and you can line them up, side by side.. to see which ones offer the best things for you and your family. The website also features Certified Pre-owned vehicles, so that way, you are not getting into a potential used car, that was treated badly. If you are going to buy, brand new. Here, you will also see the fair pricing for these cars, or trade in value of your car. I too am looking for a new car right now. To make sure I am getting the best deal, I always like to blue book the car, and see if the price they are asking is fair. If not, I print it up and take it in to show them.
Furhermore, buying from a car lot. Go the VERY LAST day of the MONTH!!! They need to reach a quota and they will give out the BEST deals on the last day. They often will take a hit on their end, just to get the car off the lot. Also, they are selling good deals, because they are making room for 08's. Which makes it also a great time of year to buy. Just remember. If you find a used car on the lot, or even a new car. Blue Book it first, print off the price, and take that in. Say this is what I want... for this price. You will find that they will have a hard time telling you No. I bought a car this way. I printed off the price, ended up only paying $500 more than the what the website said, but 4 grand less than the sticker price.
Good Luck, and I hope this helps!
~H.