I haven't picked one, still needing to do some research. I have found then at J P Cycles, Crutchfields, Ebay. Most come as a kit that include the ignition box, sending unit and even a start button. Prices I've seen go from $35.00 to $100.00.
My plan is to mount it to the side of an oil tank I'm using to hide all my wiring in. I'm probably going to use a different start button since most of the ones I see are 1"+ in diameter and I want something small and inconspicuous. Just an idea for you. Good Luck!
It's only illegal if you get caught.
If at first you don't succeed, use more lighter fluid
95% of Harley Davidsons ever made are still on the road... The other 5% made it home.
New Baltimore, Va '82 CB900c, 1980 CB985F/K 'Mutt"