I recently bought this mechanical keyboard from Aliexpress, Aigo A68 (~46 USD). I did a more in depth review in my blog with more pictures. https://0x00.cl/blog/2023/mechanical-keyboard/
If what you're trying to do isn't too complex and you don't mind being "tied" to the computer, you could get quite far with kmonad ot something similar.
Although I wouldn't want to do without qmk anymore...