As a hobbyist guitar builder (I don't dare to use the title "luthier") I cannot afford to buy custom parts from small shops or famous companies. They cost a lot and production time is long plus designing everything from scratch just takes time. I want to build something, well... semi-unique with decent hardware and reasonable costs. Is it possible? Five years ago it wasn't, but now I can say yes.
Let me introduce two of my favorite places in AliExpress to get some mojo to your guitar:
SG Musical Instruments
https://www.aliexpress.com/store/2678176?spm=2114.10010108.0.0.5bc7d141wMSIEu
Hand carved aluminium and other metal parts. Pickguards, jack plate covers, cavity covers... What I like about this site is that they offer their designs in custom sizes. You cannot draw your own neck plate and send it to them, but if it is bigger or smaller than normal, you can send your own measurements. Pickguard made out of metal is little bit too much for me, but all the small details in guitar + carving. That's what I like.
Sound of music
https://www.aliexpress.com/store/2334164?spm=2114.10010108.0.0.6d335abctfAGhF
In my opinion, this one sells a little bit better quality products, than most of the AliExpress sites. Most of their inventory seems to be in Korea (not south) and there is some pickups form Epiphone and Ibanez. Also you can find active preamps and effects you can install inside your guitar. What I absolutely love is their guitar single saddles which costs around 4 dollars /each. If you go and try to buy something similar from USA or Germany, they will cost 5 times more. They also have quite good headless guitar nut and bridge set for around 50 dollars. While it is not a Stainberg, it will do the job.
A word of caution. I found fake active emg pickups from Ali couple of months ago for really cheap price. I bought one set just to hear how they would sound. Well, it was quiet set. No sound at all. Since the set was 25 dollars, I didn't send them back.
When it comes to electronics and tuners, I try to buy the best. Lousy pickups and tuning machines is the way to ruin otherwise a good project.
Have you upgraded your guitar parts? Put a comment. It's always nice to know how people make their instruments suit their preferences!