Cheapest i could find right now to pre-order!!!!
if you are after or waiting for the big bang theory complete seasons 1-5 this may be of interest to you and give you something to think about...
current price checks to show savings and show its a good deal season 1-5 boxset:
£44.95 @ zavvi
£44.99 @ play.com
£50.99 @ thebase
yes this is not a price comparison website i know but i only state these prices to save time for people checking elsewhere for a better deal :)