I just had this done on my door. I only had one spring on there. I was advise that I needed two due to weight of door. While I really did not agree seeing I have has only 1 spring on there for 15 years. I figure these guys were shoot me straight. Anyway, I was quoted for 1 spring 125 bucks. I ended up paying 210 for two springs if this helps. Just be advised that they will try an up sell you on rollers, track cables, bolts, ect. I just had they do the springs, and yes the recommendation of two the door is not grunting when it goes up, HA so they were right. Im pretty ballzy and there is no way in heck I would attempt to do this myself.