I buy 21 shakes a week and they cost me £38. Can vary on which products you buy...the soups and shakes are £1.75 each. the bars and tetra are £1.95 each.
Also, can depend on your cambridge councellor, they can charge different.
hope this helps
Good luck
Have you looked at Exante website, can buy a monthly bumper pack online and its £99.00 per month I think!!
I like cambridge as so much variety.
Good luck with your choice