I have a 2005 19' Keystone tandem axle travel trailer and (yes I know) never serviced the axles. I pumped some grease into the zerks every few years, but haven't repacked the bearings or adjusted the ...
I did my own last year. 4 new bacing plates which include megnets, shoes, springs etc. $400. Easy to install. Drums were good. Just repack bearings. You should be able to buy complete axle asemblies for that price.