Hemi spark plug change

I was surprised to see that the manual on my 2004 Durango hemi calls for a spark plug change at 30000. My local mechanic told me if it is still running good it would not hurt to wait. I have 30500 right now and it is running good so I think I will wait. I just wondered how you other hemi guys did this spark plug thing. What was the cost?

:banghead:
Thanks,

Lancerdad
Harrison Township, Mi