I've been looking for some digital scales, and the cheapest I could find were £8 from Argos, Amazon etc. These were reduced from £7 to £5 in store at Asda in Coventry, or to order from their WWW site and collect in store. It was a bit fiddly to open the battery compartment. It takes a CR2032 button cell (one is supplied). They are simple to use and pretty accurate.