Picked these up for my little boy yesterday at Monks Cross Shopping Centre in York. They were exclusive to WH Smith for £2.99 and were available for £1 with a McDonald's Happy Meal voucher, when they first came out. Now stickered at 50p, but went through the till as £0.01 each. Not sure if this is nationwide, but may be of interest to anyone else in the York area. They had about six books left after I'd bought one of each, but I think they were mainly the Colouring and Activity Book.
Sorry I don't know how to add a picture.
First post so please be gentle!