40$ for a simple volume knob … i think there’s no point … there are severals “normal” pc-keyboards with special free programable keys and knobs for the same price … and for use with Renoise a midi-keyboard with assignable knobs is more useful …
(maybe this topic should moved to off-topic or suggestions)
For roughly 3 times that price you can get for example an Evolution UC-16
(I have one), which has 16 knobs (small, but useable) and the possibility
to store presets with sets of CC’s assigned to those knobs.
Btw: I’m not saying that one is better than other such things or anything like that. I haven’t tried much others.