Here is another site: SenDEC Products Group - Home
Look at their Inductive Meters (Surface Mount). I ordered one today; the cost to my doorstep (product and shipping) is less than $48. A picture shows you wrap the pickup wire around the sparkplug wire. There is no stated voltage source. It appears that the inductive pickup wire also supplies enough energy to power the internal microcircuit. With velcro tape, I plan on making mine portable from one bike to another. They claim the meter is good for up to 8,000 rpm.