Of course you don't have to pay the $15-20 for dealer plugs since they're just NGK or Denso. Those go for about $10 each.
There is another alternative, Bosch 9619, for only $5 each. These Bosch plugs will be fine. They are NOT those stupid 4-prong gimmick plugs. The 9619 is a normal, one-prong iridium plug that should last the same 100k that the OEM/NGK/Denso did.