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 ...
If you cannot do that yourself, I would recommend the less expensive option. New brakes on a pre-assembled backing plate are readily available as are new brake drums with new bearings for about $100 per wheel. Adding the labor makes $750 sound reasonable. Check out Big Tex (in your area near Random Lake). Given a choice, I prefer the non self adjusting brakes as they run cooler.