I have no problem with $8 for a plug. I don't know what I am doing right, but my plugs last forever. I have OS and Enya plugs that have be in use for years and been through many gallons of fuel and they are still good. I wear out engines faster than I wear out plugs. The only bad plugs I have had in 10 years of flying were when I accidentally connected one to 12 volts and when a bearing cage broke apart and the shrapnel crushed a plug's coil.