Buick92, As a minivan owner (my friends called me soccer mom when I bought it), I will tell you that the transmission is a weak point on most any brand of minivan.
I have a '96 windstar with just over 180K miles on it.
I bought it in '99 with just under 38K miles on it.
I replaced my original transmission at about 100K miles.
Since then, I have added a nice big auxillary transmission fluid cooler, and change my fluid each year with a synthetic fluid (that meets the specifications listed for my vehicle).
If you plan to drive it for a long time.....as I STILL plan to do with my windstar, I would look into an auxillary cooler, and frequent fluid changes.
My listed tranny fluid change interval is 30K miles (21K miles for "severe service), which is about a year and a half..
The bottom line, the transmission in our minivans, is the same as used in cars.
HEAT is a real killer for the fluid, which breaks down, and then problems follow.
I could go out an buy a car any time....but I don't like to waste the money, just to try to impress people....
It is real nice only having a house payment..........
As other's have mentioned, CONDITION is the big factor when buying a used vehicle.