I spotted these on a promotional unit in my local Asda superstore, last night. Asda's price seems to be about a fiver below other promotional deals on this unit and well below RRP of £34.99(according to Amazon).
According to the Salter site, this unit measures body fat by running a small current though the body. Note that it doesn't appear to provide water percentage and metabolic rate figures like some of the more advanced body analyser units.http://www.salterhousewares.com/tpages/products/npopup.asp?model=154
Alternatively, if you managed to get the recent £5 electronic scale at Sainsbury deal mentioned here(still £10 in my local!), dealextreme have a basic body fat analyser gadget for $5.18. http://www.dealextreme.com/details.dx/sku.11321