now that i know it works, i would probably spend a bit more on a better quality unit (steel instead of plastic), maybe $8 or $9! i also think that u might be better off trying a bicycle shop or similar. although it works well enough for me, my unit is only cheap chinese (i guess) plastic and is not what i would call "robust", you get what u pay for eh.
But if i wanted to spend money, i would have spent $150 on a full mojo unit. The ciggy plug to battery lead i got from kmart for 10 bucks. it doesn't seem to have effected accuracy or balance, but saying that, i was already a crap shot anyway.
Sodrat.