Yeah the game was incredibly cheap at launch in the UK. This was my first PS3 game I purchased almost exactly 1 year ago.
From a software perspective it surely didn't flop, but we knew that already at the end of 2008.
On the other end I still think it flopped, cause it was meant to attract a new audience to the PS3 or at least was hyped up to be so.
Hardware barely increased that week. MGS4 was in the end a much bigger factor, although the "hardcore" crowd already owned a PS3 back then.