I would also look into why it's being sold. Do as much checking into it as possible. Check for rust underneath, including heater lines, and front strut mounts. Check under carpet on passenger side for wetness. Check under engine for leaks. AC backlights are common to go out on these models, check to see if all the lights go off on the dash when you start it. Check for codes if all possible. If you need help with the codes just let us know. Brakes are also common to stick, check the pads through the rims if you can. Do drive it, get it to normal temp, and test it, push the gas alittle harder, stop alittle quicker, listen to the transmission shifting, listen over bumps. Take it to Auto zone or Avanced if you can and have them do a free electrical test on it. This link below will help you with what the van is worth, and mainly people who have rated it! We all here hope the best in you finding something good. Good luck.
www.edmunds.com/dodge/grandcaravan/2003/consumerreview.html