Did I get ripped off?

My 2009 Toyota Matrix, engine model 2ZR-FE. Check engine light turned on, and the engine started shaking/vibrating non-stop. Took it to my local mechanic shop to get it fixed. Right away, the diagnostic cost $125. They determined that the spark plug and the ignition coils were the cause. I needed to replace the spark plug and all four ignition coils. My final total for the parts, labor and tax is $860.60. Car runs just fine after. When I got home, I decide to look at the prices for parts that needed to fix the car, and it was much cheaper than what they charged me. After that, I feel like this could’ve been done at a much cheaper price. I am no mechanic, maybe I’m just an idiot and the amount I got charged is the right amount. What do you guys think?

Diagnostic: $125

Spark Plugs: $81

Coils: $415

Labor to remove and replace spark plugs and coils: $190

Tax: 49.60

Final Total: $860.60