Spotted this a couple of days ago (in the London, Hammersmith branch.) They had about five different ones, though I can only remember a Baywatch workout and a Nell McAndrew one. I picked up the former. Tried it out last night, and bloody hell! Does my body ache! I'm pretty fit too. For £1 each, you can't go wrong. Even if you use it once, it's still miles cheaper than paying for a class!

Recommend you pop into your local Poundland and see what they've got!