I would just want to add to this thread, when you take on a rescue dog, you're often taking on someone else's problem that they've given up on. We took on a Boxer from boxer rescue, here, and we've given it the year that they recommended for him to settle down.
He is a really friendly, character dog - but he still wants to run away, attack dogs, sheep and horses, so that letting him off the lead to run around is not an option, which makes life less pleasant for both dog and owner.
Here, the price of the dog was whatever voluntary donation we cared to make, and the whole procedure was less onerous than the one outlined here. Since then, vets bills aside, he has cost a fortune in higher fences etc. etc., and now, we've paid out a small fortune for an animal behaviour expert, whch is fine, but adds to the cost - I can't help thinking that taking on a puppy, with all the papers, to train ourselves, would have been cheaper!