£20. Can get bucket loads of them for the price of a Chris King.
Anyway, despite what some people seem to do with them I find they last years without complaining and then can just re-grease, but then £20 replacement who cares.
Just treat them right. Torque cranks correctly to spec, not LBS gorilla tight, not too loose. Load up with loads of grease. Don't pressure wash. No GT85! etc.
Though I end up greasing the bearing surfaces frequently as I'm often taking the cranks off for one reason or another like many changes I've made to chainrings, chain guide and cranks themselves.
Tip though - a rubber o ring or two where the gap is on the drive side between dust cap and crank (yes there should be a gap of a couple of mm there)... helps stop the plastic dust cap rotating off and letting dirt in.