My Lab Holly had the same TPLO surgery 2 weeks ago, cost £2500 so thank god for insurance. She's recovering very well but will be out of action for this seasons pheasant.
Very sorry to hear your friends dog had to be put down Frank.
For anyone else in a similar position its always worth giving the RVC (Royal Veterinary College) at North Mymms a ring, they might be able to offer a solution using your dogs condition to teach vets surgical techniques & you get free treatment.
Chris