You can go to the parts dept. at the dealer and have them look up the part number for you. Note- I have found that some parts guys at some dealers that should not be there as they don't know how to use the computer to find the parts. You can go to an online dealers website and probable look up the part number by doing the research yourself. I have found a lot of parts by doing it myself. Takes some time though to do it. You can also check out local salvage yards to see if they have any Dodge or Chrysler minivans the year you are looking for.
The pic below shows OE part numbers for both pieces and dealer prices for me locally. The prices usually vary with your local dealership, but should be in the same general ball park. Given the absurd prices the dealer wants, I'd try local salvage yards before anything else. car-part.com has always been my go-to for these situations. It's a third party website that allows salvage yards to post their inventory and, usually, their prices as well. But, trying to identify what they might call those panels vs what the OE calls it might just make it worthwhile to go old school and visit local salvage yards directly, show them what you're looking for and go see what's physically in the yard. I don't know what applicable model years will interchange, but I'd at least look at any junk Caravan 2008 through 2015 while searching.