Internal fan controller or mounting controller inside case

[Kogi]

Some of my case fans run at 2000 RPM so I'm searching for a good fan controller that can be mounted inside the case. Alternatively, I'm looking for ways to mount a regular sized fan controller inside the case. Looking to spend up to $20 maybe $25. I would really like a fan controller to be inside the case but maybe an optical bay mounted one would be okay as long as it looks nice on my case.

 

 

 

Random details: I have a windowed side panel, black case, color scheme is red, front panel is mesh

 

 

This is my case: http://www.newegg.com/Product/Product.aspx?Item=N82E16811119298&cm_re=cooler_master_n600-_-11-119-298-_-Product

[LogicalDrm]

You can turn any 3.5'' or 5.25'' bay device around. As fan controllers are generally shorter than normal bay devices, you could easily have one facing inside case and leaving cover in place. If you don't want to use controller, you can buy voltage reducers for fans.