OMG... Can't believe that I didn't found this earlier.
The AKERS BARNES cockpit.. Apparently, it seems that it fullfills all my needs. As cheap as possible, and very very customizable.
If I were to build the ABC, and make the joystick detachable, so that I could put my mouse where the joystick usually are, that would make it perfect for FPS.
And maybe mount the keyboard on a board with velcro, so that i can attach it on the edges on each sides of the seat. When not in primarily use, it could be attached over the wheel.
And maybe mount the pedals on a board with furniture-wheels, with some kind of a spring loaded latch to lock it in each position...
Does anyone have any experience with the ABC? It seems a bit low, and the seat seems a bit inclined, is it uncomfy?
Here's a rough idea (borrowed the original ABC 3d drawing from 3d warehouse on the net):