Don't know whether this is any help but just had my mares leg x-rayed. 2 plates were £108.33 and 2 extra plates at £25 each. Total bill will call out was £266. It all depends on how many plates are used and I would expect it to be considerably more with a vetting.
EDIT: just double checked bill as total seemed high but it was almost £40 of VAT too!
I have got a vetting tomorrow and have to have 18 done for insurers! I shopped around and the best I could get was £362 for all 18. May need a sedation charge too which is normally about £25. Best of luck with yours! What are you xraying?