Hi! I am gonna try make my own midicontroller and i need some help!

question 1: Where can i buy components for my midicontroller?

question 2: can i use these knobs? http://no.mouser.com/Search/ProductD...8-RK09K1130A5R
I will try make it as chesp as possible

Please komment if you have an awnser for my post

Tnx for your attention