Hi bvgs
Expect to pay somewhere in the region of £10,000.00. (The cost of the kit, fitting and any paint work repairs) I have had the work done on mine and it took around 4 weeks to complete.
I have heard that the compliancy date has been moved forward to the end of December 2013 now as opposed to December 2014, so I would imagine that as we get closer to the expiry time the costs will likely increase (on the assumption that many owners/operators will probably leave the procedure to the latest possible time)
Best Regards
Rich B