Misfiring Mitsubishi Pajero

I recently took my 1996 dual-fuel Mitsubishi Pajero 3500 wagon to a mechanic to fix a misfire. It was there for two days and had new platinum plugs and leads fitted. I was charged $136.90 for the plugs and $127.10 for the leads, and then $225.00 on top of that for labour. Your opinion would be greatly appreciated whether this is excessive for the work carried out on my vehicle. Do you think that's excessive?

The cost of the plugs and leads is about right, and the labour charge is about right for three hours work. If all he did was fit the plugs and leads it's expensive, but if he investigated the cause of the misfire beyond simply fitting those parts the labour charge is probably about right as well.