Ours came to a lot more than we expected. I think the wills were about £250 each - I had thought that one between us would have sufficed, as they are mirror wills, but we had to have two.
To be fair, though, the solicitor who did them was very good, and asked us all sorts of things that we would never have thought to consider if we'd done them ourselves, and she had a set fee rather than an hourly rate, so we never felt rushed into making decisions.
The LPAs were the best part of £2000 for two of us, as we each got both health and finance ones, so that meant that all four of them had to be registered, and that was where a lot of the expense came in.
To be honest, with hindsight I would do the LPAs ourselves, as all the questions are there, and you just have to answer them - there is nothing that could be missed out, as there is in a will.