My Toxic '74 Duster

for some reason that i do not understand if it is made for a mopar the manufacture thinks it' should cost twice as much as the same part for a chevy when in reality that fabricated sheet metal,tubing,piece cost exactly the same in raw materials.

I am kind of cheap, but I somewhat understand why.
1, for a manufacturer to research a part, make up then test a prototype, then tool up to manufacture in quantity to then sell 1/4 as many as you will sell to Chevy guys -costs more
2, Mopar guys are notoriously cheap, and by that, I don't mean that in a bad way, but since a lot of our stuff is higher priced, and a lot of our stuff was good from the factory, we don't like to spend the money on stuff that we can get by with.
3, whether of necessity, or because we are kind of "thinkers" we tend to be able to craft our own stuff, thereby shrinking the market even further for a given part.

There's probably a few other reasons, and I (like most times) am probably wrong, but Yeah-building a Mopar ain't the cheapest entertainment as far as hobbies go.