I'm about to have one of my fourteen crowns replaced (don't ask - it's a sore point), so have just had the rundown on NHS dental charges.
Basically, you now pay one of three charges: �15.50, �42.40 and �189.00. Crowns, bridges and dentures come in the upper band. The cost is per course of treatment rather than per tooth, so if you have two crowns done in one go, then you'll only pay �189. Have them done in two seperate courses of treatment and you'll pay that charge twice.
The good news is that �189 is the maximum you'll pay for any one course of treatment. There's more information here:
http://www.nhs.uk/England/Dentists/DentalCharg es.cmsx
If you have private treatment, the dentist can charge what he or she likes.
Nine years isn't the longest time for a crown. I've had some of mine for nearly thirty. My dentist tells me that fifteen to twenty is about average - depends on the material they're made from. Again, more info here:
http://www.dentalhealth.org.uk/faqs/leafletdet ail.php?LeafletID=7