The x50s came out in Sept or Oct 2010. Here's a thread from the end of April 2011 about BestBuy and Border's having them on clearance, and referencing other threads already mentioning the clearances even before this thread:
https://www.mobileread.com/forums/sho...d.php?t=131279
So the x50s were also starting to be cleared out after 7-8 months.