I have been looking for the source of the stacked black knobs they use on sadowsky basses, i found them at bessbassgear.com but they are selling them for $18 plus shipping, which i think is ridiculous, and sadowsky charges around the same. Do you guys know where can i find something at least similar? they are black machined aluminum with a white stripe marker. here is a picture. http://www.bestbassgear.com/images/other/concentric-alum-knob-large.jpg thanks!