We don't have a set price to quote here without seeing the door, the opener you have now, and what shape the header and track are in - that's the honest answer, not a dodge. What we can tell you is what drives the number: whether you're getting a belt-drive or chain-drive replacement, whether the existing wiring and bracket can be reused or need to be redone, and whether the mounting point needs reinforcing, which comes up more often in Mirrormont's older stock than in newer construction nearby. Cold-climate lubrication and weatherproofing on the unit add a little, but not much, given the moderate-cold conditions out this way.
One limitation worth saying plainly: if your door and springs are also near the end of their life, we're not going to recommend a new opener on a door that won't hold up to it. Sometimes the right job is the door first, opener second, even if that's not the call you were expecting.