Akai LPK 25 is like $50 brand new, so is LPD 8 if you're more interested in pads (MPK Mini gives you both for $100 new). There's cheaper options out there, but that's the cheapest I know from a well-established brand.

Even if you have no interest in music, get one. MIDI is super easy to read, you can DIY something like an Elgato Stream Deck for a third of the price, physical volume knobs included. It's up there with a Raspberry Pi for the coolest cheap gadget.