That's a lot more than I charge! A LOT more. And I get concerned when it's not returned in a week!
Sometimes it's taken three or four weeks and I feel rotten about it.
That's a tough question whether a novice could do this or not. There are skills and tools needed for the job that not everyone has. I've been opening up things my whole life, and the first ones didn't always fare so well. But with each failure or mistake, I learned. So I guess it depends on your mechanical aptitude and patience. If you're a very patient kind of person and enjoys (or can handle) working on small things and making, what seems like, very little progress, then you probably can do it.
Sometimes the simplest things can take quite a while to do right. You'd think removing a bezel is simple as just opening the crimp. Well, yeah, unless you want to re-use it and have it look like it's never been off.

There are instructions on the net in various places, and not difficult to find. And yes, the problem with the odometers tends to be a certain pot-metal gear that slips on the shaft. Guys have reported success in carefully JB Welding the gear to the shaft. Sometimes that hasn't worked, but may have been because the surfaces weren't totally clean of oil or not given enough 'tooth'. I do a fix that fixes the gear solidly in place and definitely prevents any unwanted movement.
Sure - you could send it to me! In pieces or whole. It doesn't sound like it needs any machine shop work (shafts, bushings, etc) so count on a week, maybe less.