This may be my most frugalfarkle (8mm bolt and nut from the metric junk box).
Part II (only for Concours 2-piece clutch and brake levers) If you need to replace the outside part of the clutch lever on the road (due to parking lot tipover or whatever), I found that you can use the corresponding part of the brake lever upside down. The normal attachment bolt doesn't fit, as things don't line up exactly, but you can substitute the same bolt and nut from above. At least this way you can ride, clutch, shift and you still have the rear brake. It even adjusts!
That makes this a dualpurposefrugalfarkle.