It depends if I want to use them in cooking or eat as they are. I like the really soft squiggy ones not the ones with hard skin as I mostly eat them straight from the packet. Or cut them into pieces and drop into cooked porage. The softer ones are more expensive I think. Costco's are good with some soft and some hard but a brilliant price as per most of Costco stuff.
They're £5 because M&S know that rich people, like SandyRoe, only read the price on the receipt after making their purchase, whereas the rest of check the price in advance!
;-)