How many miles is just too much to consiter buying used

Yes I am about to buy a new to me Dodge Caravan or Chrysler Town & Country mini van. Something to replace my ailing 99' Chevy Suburban. I am looking at 02' to 06' models. Any newer then that would be out of my price range. I would like to keep the price down to $6000 or lower. I see mileage go from 80k to 140k. Just wondering when do these things quit? How many miles would just be too many. Any help would be greatly appreciated.

Thanks, Gold Top

My 02 has about 100K miles on it now and it I use it like a truck. I haul a 2000lb camper, I put 500lb+ payloads inside it and it is driven frequently. It has yet to let me down. They are great vans and with proper preventative maintenance they can easily do 250K+ miles. Best minivan built for the money and I should note I am a hardcore Chevy guy too.