This is just a heads-up if you are going to Sainsbury's anyway as this might have been a specific store mistake.........
I was able to buy three 2nd generation iPod Touch 8gb at Sainsbury's, Pound Lane, Norwich, for £99 each. Pictures below to prove as I couldn't believe the price I came across either!
No hassle at all from sales staff, they simply put it down to an error. NOTE: They removed the shelf label as I left so no good going to Pound Lane.