I recently got a new, in-shrinkwrap copy of River of Cradles for RQ3 from titan-games via e bay. I was a little dubious about it being "new, in shrinkwrap", but decided to punt the $40.00 (including shipping to the UK), and am actually very happy with what turned up in the post. They apparently still have 9 copies available.
PM me if you want any more information.