This is just a fun deal I saw in Tesco when I was in there yesterday evening.
I'm afraid I don't remember the price of the boxes, but when you buy the 160 bag box, you get another box free. And to top it off you get a free "monkey" from the adverts - ones with sucker hands so you can put them on a window.
I can't see it on the website, but they were right in the front of the shop in the Burton-on-Trent store, so I guess it will be similar in most other stores.
Not for everyone, but great if you've got kids - or if you're a big kid like me!
I bought some today - they were £2.93 per box and BOGOF.