The 16GB model was £399 at launch, 32GB was £479, and the 64GB was £559 (all exactly the same as the iPad).
The PlayBook is being sold at a massive loss for RIM, and is already a hugely expensive failure. I think that the only reason RIM hasn't done as HP did with the TouchPad and just killed it off is that unlike HP RIM doesn't have anything else going for it other than its mobile devices... It *needs* the PlayBook to survive, and is making a rather large gamble that things will be OK in the long run so long as the PlayBook builds up enough of an install-base to eventually help things turn around for the company...
£129 for a 64GB tablet is excellent value, but as mentioned it has limited support. Still, if all you want is browsing, email, and media then it is a great choice.