https://www.reddit.com/r/customGCC/
This subreddit runs a discord with a ton of people who can fulfil these requests. Since it's individual creators, it takes a little longer, but seems to be cheaper than sites like multishine/cc/etc
I''d check out the disc, then look into getting a commission. As always it's cheaper if you supply your own controller or shell, but a lot of the creators have a stock pile, or current stock of assorted colors.
Common mods I see getting done there:
- custom buttons
- custom colors
- snapback capacitors
- trigger plugs
- analog to digital z buttons
- general maintenance
- paracord sleeving
You may have to go some place else if you're looking for more precise things like Melee notches or something.