$460 to change the spark plugs ???
 

Wife has a 2103 Civic Hybrid with just over 100k miles.
We let Honda change the oil and rotate the tires.
Her last visit Honda quoted her a price of $460.48 to change the spark plugs and $409.96 for a valve adjustment.
Now having any issues with the car, just what they call "its time for" these services.

Now.....$460 to change the spark plugs. WTF is involved in changing these plugs that cost so much?

Sounds like it's time for you to learn some auto maintenance skills so you can change plugs and even adjust valves. I really doubt that your valves need adjusting, but this is just what the dealers do to make more money. Most dealers get upwards of $100.00 an hour for maintenance work. My wife took her 2017 CR-V Ex in for her free oil change. They tried to tell her it was time (17,000 miles) to have her brake fluid changed. Yes, her brake fluid. They said it was a standard maintenance item and costs $164.99. She called me from the dealer's and I told her just the free oil change. Nothing else. Beware when you go to the dealer. They're in business to make money!
Duane