Available at the Fresh Fish Counter. Advertised at Half Price, although still seems cheap at full price. Does not appear to be online I am afraid so a trip to the store will be required.
There are unfrozen (or partialy frozen) ones on display, although they are usually happy to sell completely frozen from the chillers. Great for stocking up the freezer at home.
Also have the Peeled version at half price - 80p/100g (£8.00/kg) if you are feeling a little lazy - still a very good price for the product. Personally I would let them thaw and peel them myself for the difference.
Fantastic for Paella and all other seafood dishes. Enjoy!