A half-shaft is about $89-99USD at a parts store and it includes two new joints. I've always heard if one joint is going (the boot tears, then the joint gets eaten by sand), the other's not far behind. Both times I've had a bad joint, I've done the full shaft. I don't see how it could involve any more labor and definintely less than if you have to do it all again to replace the inner joint! I call it 'insurance'. -scott