I personally did this my self i think its cost me around 200 or so but i change the plugs while i was in there too so, yeah its a big pain in the butt, because the way 4runner engine is designed, you have to take off TB, drain some coolant, disconnect some cables, air hoses, intake, coil pack, even then its a tight squeeze to get the covers out, make sure to put some silicon on the edge of the valve cover while you at it just to make sure. good luck.