I paid the equivalent of $4 USD per plug at Rockauto. Local parts stores will rape you on any plugs, even if you pay shop prices.
Iridium plugs are in the $15-20 range up here. Hence why Rockauto is my to go place for 90% of parts on all our family cars / trucks.
Besides, iridium electrodes just don't burn. That's why some manufacturers are now using them as "lifetime" plugs, especially on sideways mounted engines with difficult access to the rear bank (like Lexus / Toyota). If I don't have to do them again in the next 10+ years, I'll be a happy guy and will gladly pay the extra $10 for all 8 plugs!
I'll pass on manufacturers with "lifetime" plugs..of course the lifetime of the newer engines won't be 250-300K like the old ones we were accustomed to for over 20 years!
Even the 100K mile plugs and tune up was way to far.
Coils, wires, and especially boots start to misfire near 100K often plus there is plenty of crap that works it way down into there that I want to blow out before it gets too far past 100K or so.
Local parts stores are starting to rip people off badly on many parts. They don't seem to realize volume at lower prices would be better than sales continuing to dwindle at higher prices and profit margin. They keep digging their own grave. Eventually there will be an Amazon Auto Parts retail store or you will be able to go to dist center to pick up or have them to your house in less than 2 hrs as they do many places already.
I have no issue with Autolite platinum or Motorcraft platinum plugs that I get locally for under $3 each.