I have a carport that is finished outside of garage doors. It is two bay, 9x7 doors. It is already wired for the openers and the ceiling outlets are wired to switches by the door.
The previous homeowner never put doors on because he had an extended bed truck and it would have totally filled whatever side of the garage it was in. The interior walls are covered with the same vinyl siding as the rest of the house over sheetrock, which while a little odd isn't that unusual, and it was well done and looks nice. The ceiling had a matching color of vinyl that covers it.
I went and priced doors and openers at lowes and HD over the weekend for a ballpark (I'm sure there are better out there). For uninsulated windowless doors and two 3/4 chain drive openers it looks like I'd be in it for about $1000 in parts. I was surprised to see that springs, tracks, and the associated parts are included with the doors, which I really didn't expect.
I called a local company who came out last week. I got the impression that their estimator was new and out of her depth... she wasn't able to answer any questions and was concerned about which way the ceiling rafters ran (it's very obviously a trussed roof and has a hatch to access the area up top). She was extremely concerned about whether the vinyl siding would get in the way of the install, which seemed an odd thing to be so concerned about... you could screw into it or cut it with a good utility knife.
I didn't ask questions about or expect preliminary answers on price, but she deferred practically every question I had to "I'll have to ask my boss" and told me she'd have an estimate thursday. I didn't get it until this morning, and it was $1700 all in. While the price isn't a show stopper (although I think it seemed a little high, there aren't a lot of residential garage door companies here and I could live with it if it came with warrantied work, although I'm not convinced there is ~700 in labor in this job), when I called her to ask I was told that I would also have to buy "pads", which were $50 each, and that I would have to remove the vinyl siding in the areas where these "pads" would be installed. When I asked how I should know where to remove the siding she stated "oh, it's about the size of a 2x6 and about 16" up". I was polite but I told her if that was all it was I could stick a 2x6 to the wall for a whole lot less than $50x2. I was told that their installers did not want to be responsible for cutting any of the vinyl siding and apparently she thought I'd start hacking the finish off the walls without knowing the size or placement of some part I know nothing about.
So i went from being simply baffled about whether the estimator knew any more about garage doors than I did (jury is still out, and I don't know shit) to thinking they just really must not want the job. If nothing else i just found it unprofessional to send an estimate and then immediately tell me i need to buy more stuff from them to even have the install done, in addition to doing the prep work myself.
So, sorry about the tl;dr, but how hard is installing a garage door? It doesn't look all that complicated but sometimes you don't know what you don't know. Again, the wiring is already done.