I replaced the gasket in my B190 at one point, and I think it was closer to the $140 that n2916s had. It helped the fridge, definitely. It wasn't the easiest to install correctly, I had a few issues with it coming loose but finally got it all working.
I think the test is to put a dollar bill or piece of paper between the gasket and the frame, close the door, and see how hard it is to pull out. No point in replacing it if its not bad.
1995 Airstream Classic 30' Excella 1000
2014 Ram 2500 Crew Cab with Cummins 6.7L Diesel
Sold but not forgotten: 1991 Airstream B190
Sold: 2006 F-250 6.0L Powerstroke Supercab