Yeah, get the cheaper one and add to it as you need to. As far as the torque wrench goes, I'm personally not bothered by 4%, but that's me. Alon is probably right, buy the best one you can afford. I doubt you'll need one anytime soon unless you have a job in mind. You won't use it as much as you think.

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Kyle De Priest
2007 e320 Bluetec
2013 GLK 250 Bluetec