We've used Data Recovery Services - Oxford London Birmingham Leeds UK just recently.
You send the drive off, they inspect it (can be FOC) and then quote you. Upto if you feel its worth it, if not they send the drive back. Superb service. I filled the form out, and they rang pretty much straight away. Always in contact via email and phone- keeping me informed.
They were also very 'clued up'. Discussing RAID etc, which drive failed etc.