Had a local guy quote $ 1,900 for new rotors and new calipers on a dual axle Shoreland'r
That number gave me an instant nose bleed so I figured I'd try and educate myself with a few Youtube vidz and do it myself.
It was time consuming (getting the old rotors off with zero clearance for tools on the axle flange) but in the end, I was left with a warm fuzzy feeling of having been self-reliant (and an even warmer and fuzzier feeling for having saved some dough)
$ 550 for calipers and rotors + $ 30 for brake cleaner and DOT 3 fluid + $ 100 to my neighbor for helping me bleed the brakes = $ 680
Here's a before and after so you guys can see what things might look like behind the tires of your trailer after 5 years of salt operation: