I'm confused. How do you buy a seven year old truck and get charged that much for an audio system? Did you buy pieces from the dealer afterwards?
If so, you should be aware of the differences in the radios. The Infinity and non-Infinity radios are identical except for a few components in the output circuitry. Infinity radios put out much less bass. It is made up in the amp(s). If you use the non-Infinity radio with the amp under the seat, or little amps bolted to the speakers, you will have to turn the bass way down for it to sound normal. Infinity radios without the amps will sound tinny. Unlike some of the confusing older Ford and GM mix and match systems, all Chrysler radios put out speaker-level output. Any Chrysler radio will work in any car with any speaker combination, with or without an amp. That's not to say any combination will sound good. The amps do not increase volume. They are strictly for tone conditioning for the specific vehicle. Using the wrong speakers will adversely affect the sound too.
I repair and sell a lot of radios at the nation's second largest old car show swap meet. The Chrysler cd / cassette combo radio is by far my most popular unit for upgrades. They are built by Mitsubishi and are very high quality. The cd-only radio is built by Alpine. Both have a few issues related to automated manufacturing techniques. Once repaired, they're repaired for life. Very few people complain about the sound quality of these systems, but most owners are simply looking for a "utility" system that sounds pleasing. Perfectionists who are more concerned with building home system quality into their vehicles may not be pleased, but people who consider their cars as just basic transportation are usually happy.
I can't argue that oem systems are overpriced. The Infinity cassette system came as part of my '88 Grand Caravan and sounds very nice. (I am not a perfectionist). I ordered the Infinity cassette system as part of my '93 Dynasty. That system sounds fantastic. The car only has 4,000 miles, but sometimes I sit in it just to listen to the 6-disc changer I added. With all the package discounts my dealer gave me, the Infinity system didn't cost very much extra at the time. For less than an extra hundred bucks, I got ten speakers, the rare remote amp, and an upgraded radio. As proof these systems are designed for the specific vehicle, some of the newer cd players do not sound as nice in that car with those speakers.
I'm sorry you don't like your system. You might investigate further if the components are matched to each other and are meant for a truck.