I service the odd 1120 based watch now and then...
馃槈
The 1120 isn't any more expensive to service than any other automatic movement with date. I personally charge the same labour for this movement as I would for a Rolex 3135, or a vintage Omega 565, or a watch with an ETA 2824-2. What has the potential to make it a more expensive service is if parts are needed, and specifically what parts those are. Having said that, the parts for this movement are pretty inexpensive overall, when compared to say a vintage caliber like the Omega 565.
I gave this example in another thread recently - reversing wheel for al 1120 on the left and one for a 55X/56X series on the right. Left is $14 and the right is $104.
Although any competent watchmaker can service an 1120, contrary to popular belief the 1120 is not just an ETA 2892A2 with different decoration. Many parts are not interchangeable between the 2892 and 1120, for example the bearing for the rotor is completely different. This is an 1120 bearing mounted in a fixture for assembly to the rotor:
This is a 2892 bearing:
I replace the bearing in probably 50% of the 1120's I service, so this is a common part that is needed, so access to parts is a consideration, even if abilities of the watchmaker are not.
Cheers, Al