This link might be helpful to estimate the customs fee on your Stowa (or other) watch imported into the US: https://hts.usitc.gov/?query=%22wrist%20watches%22
I recently purchased a Stowa Marine Automatic with the basic movement and basic leather strap and was surprised to see a $66 FedEx customs bill show up a few weeks later. I understood from previous posts that the customs fee should be about $25-$30 for that type of watch, but seems like everyone ends up with a different rate. In any event, it looked like FedEx calculated a flat 8.8% rate on the watch, which seemed high to me.
The customs rate you pay depends on a lot of factors, such as the type of movement, number of jewels, and material used in the case (clad in precious versus non precious metal). In any event, it appears that the Marine Automatic should be under category 9102.21.70 ($1.53 per watch + 4.2% on the case + 9.8% on the strap) since it is a wrist watch that is not clad with a precious metal, having automatic winding, having over 17 jewels in the movement, and with a strap.
I called FedEx to explain this and they just said to disregard the whole invoice and that they would write it off. I did not expect them to do that, but in any event it helps to understand whether they are charging you the correct rate, and at least they are very accommodating in fixing it if they charge the wrong rate. In my case, it looks like they might have charged the 8.8% rate for “other” watch straps, watch bands and watch bracelets, and parts thereof under 9113.20.90.