With fan controllers you have to be careful. Excluded those PCBs linked above, those are nice, but with those $30-$40 5.25" bay controllers you can typically only run 1 or 2 fans per channel. A lot of people cite problems with channels dying quickly or not adjusting the voltage well (assuming you are using 3-pin fans). For example I had that NZXT Senty2 for a bit on an old PC and it really only worked at 100%, 60%, and 35%. Anything in between did nothing.
The AquaComputer Aqueros are pretty expensive. But seeing as how you can run 20 fans per channel and a pump and have full control from 0%-100% even with non-PWM fans is probably why it's so expensive.