My car needs work. I have a reasonable budget. The check engine light is on and I need it to go off so I can get an inspection. I do NOT fix cars.

I took it to Advanced Auto and had them put it on the machine to figure out why the check engine light is on.
Cylinder misfire- the guy tells me I need a tune up. YAY! I figure this should cost less than a 100 bucks. WRONG!

The guys at firestone tell me its going to be 267 just for LABOR! Then 60 bucks for the tune up. I feel this is outrageous! But they said my spark plugs are under the engine and its going to take alot of work to get to them.

Anyway, my question is this- is that reasonable? Is it safe to take it to a shadetree mechanic who will charge much less for the same job? What would be a reasonable cost from such a person (shadetree mechanic)? I already bought the spark plugs. Or is this one of those complicated jobs that only a "professional" can do.

I can afford to pay around 150


Thanks for your help.