You can get kits starting at about £50, but you may havevto buy more chemicals etc. The machine I bought, along with the chemicals originally cost £1200!!! I paid £100 for it and then about £25 for the gold solution.
The knobs must be in good condition to start with, no dinks or missing plating showing the plastic.
You then need, along with the plater and mulitple swabbing probes, goggles, mask, gloves (don't do it in an enclosed space):
Chrome stripper
Nickel activator
Alkaline cleaner
Distilled, de-ionised water
Gold solution 9/18/22/24 carat (the higher the carat, the golder the colour. Mine was 22k)
Gold cleaner cream which also seals and protects it.
It can get expensive! Luckily, I did my Cobra, my Astatic 575's cable spring and plug, some other mic' plugs, the chrome necks on a couple of Sadelta base-mic's and a few other bits before I resold it for a few quid more than I paid for it all.
I also stripped the chrome off my Renault Espace's front and rear badges before I painted them black
