Congratulations on your acquisition and welcome to the forums. I just had disc brakes and brake lines installed on my Classic 30 trailer and it took about 2-3 hours of labor. Labor and material prices vary widely, so your best estimate for the repair should be from the shop that has it. In Florida, it is a legal requirement for auto repair shops to give an estimate and get it acknowledged before starting work. It may not apply in RV shops and Maine may not have a similar law, but the shop is still your best bet. Total price for the brake line part of my job, including the lines I bought, was in the $350-$400 range. I'm guessing at the labor because I had axles replaced and calipers mounted in addition to running the lines to the calipers, but I ran the main line from the actuator to the vicinity of the first caliper.
"You cannot reason someone out of a position they have not been reasoned into"
Al, K5TAN and Missy, N4RGO
2002 Classic 30 Slideout
2013 Dodge 2500 Laramie 4x4 Megacab Cummins
2001 Safari 25 RB Twin (Gone, but not forgotten)
WBCCI 1322, TAC FL-39, AIR 82265