A cheap 75% and pretty good mechanical keyboard is Ajazz AK33 (82 keys), black switches ( zorro switches, which are clones of Cherry MX). I've paid 30 € for mine and so far I'm very satisfied on how it's works.
The only thing I did not like was the shining bottom which was like a magnet for fingerprints so I've moded it.(sanded, painted and added some sponge/foam to block that resonating sound for the keyboard box).
Before:
After:
The only thing I did not like was the shining bottom which was like a magnet for fingerprints so I've moded it.(sanded, painted and added some sponge/foam to block that resonating sound for the keyboard box).
Before:
After: