Boxes of Persil Non-Bio tablets (12 washes/24 tablets) at Tesco for £1.
Other brands were over £3 for 12washes
Edit- 12 washes sorry, got no idea where the 11 came from! ha
Seen as some people can't be bothered to read other peoples posts, I got these from the Grimsby store (Victoria Street) and they were down the aisle with, you guessed it, fabric softener, wash powder etc lol