From stores, they always sell it at the RRP of £3.49 (about $5.99/$6.99) in the UK - unless there is a sale which there never is. However, I'd never be that crazy to spend almost £4 on ten pieces of paper so I purchase them online instead for about £2.75 a pack, or I get tins which equals out at about £2.50 a pack.
Anyway, I rarely buy them (too unlucky), the only time when I buy them is when I just want a surpise - it can get quite exciting! xD Darn, this post is pushing me towards buying some!!!