If you want to avoid shipping costs, just go to Walmart for ATF+4 quarts. Make sure that the fluid meets Chrysler MS-9602. Walmart has brand name filters as well.
The dealers sell ATF+4 in gallon jugs and some in bulk oil gallons to customers if you bring in your own clean empty jugs.
Not all dealers will do this. It helps if you are a good customer and know the parts guy. This could be cost competitive with buying it in the quart size.
The dealer should have no problem taking in your waste oil as well.
Welcome to Allpar. ATF+3 is no longer available. It is superseded by ATF+4 which is a synthetic and fully compatible with what you have now. It outperforms conventional ATF by a large margin, gives longer clutch/seal life and it is worth the cost. Always drop the pan and replace the filter (the o-ring has a tendency to stay in the valve body so make sure that you pull the old one out before installing the new filter).
If you haven't already, there is a software upgrade (see TSB # 18-24-95) for your TCM which greatly improved shift quality/torque converter lock-up feel and transaxle longevity that is also highly recommended.
Heat can kill transmissions. Make sure that you can flow ATF through the radiator cooler still. If these plug-up or restrict (and they did), the transaxle will have a short life. Once plugged, the radiator should either be replaced or an external cooler installed.
ATF+4 replaces ATF+3 in all applications.
I doubt you'll find a $150 scanner that can access the transmissions codes. A used SnapOn MT2500 with the proper Chrysler cables and domestic cartridges is one that will do it but but I don't think $150 will get one of them.
One of the first questions of any shop working on a Chrysler transmission is what fluid they use. If they hesitate, mention a universal fluid, an additive or don't specially mention ATF+4, more on.