i found out what aldi is doing a while ago. they put these special offers on to get people in store, but they make sure they dont have any stock in store prior to the start of the sale because they cant afford to sell things that cheap. it was the same with the laptop, and the satnav etc etc etc.
if you go in the day before the sale they will usually have them in stock, but as if by magic the morning the sale starts they're all gone. i tried to get the laptop, and the satnav, i even tried to preorder the satnav, but both times they "sold out" when i got there on the 1st day of the sale. i made a bit of fuss about the sat nav offer and the store manager told me that they wouldnt have them in stock any where in the country and they couldnt get me one because they arent allowed to, but if i wanted one the day after the sale then they would have them in stock again.
surely thats illegal, but i think the "while stocks last" disclaimer covers them legally.