Amazon.com has both the 20″ and 22″ Diamondback 2012 Response Mountain Bike on sale.
Click here go to Amazon listing
As of today, July 2, 2012, the 20″ (large) is $266.41 and the 22″ (XL) is $285.75.
The list price on this bike is $450. The normal sale price on Amazon is $325-$337, so this is a terrific price.
2 Day shipping is Free with Amazon Prime (heck, spring for overnight shipping for only $3.99)