Tesco have the ready made shakes 6 pack for £4.00 saving £2.98, 3 meal bars for £2.00 saving £0.98 and Smoothies 2 for £2.00 saving £0.34.
Asda have the tins at 2 for £7 and the single ready made smoothies and shakes at 4 for £4.00
Boots have 6 for 5 on all Slim Fast products (presume cheapest item free)