Welcome to the forum.
You may have already checked on this one from Arkansas Valley Diesel throgh ebay. It's $750 but I'm not sure what your quote was from Freightliner. I'm thinking that you'd be able to find a used one somewhere through a salvage source if you have time to search around for it.
AIR PRESSURE,4N1, OP/CT, POLISHED W22-00013-022
Arkansas Valley Diesel website
I also see some when searching around that have a white face or a black face with a black bezel but those, of course, will not match your application and would look terrible.