cost depends on your CDC hun, some charge slightly more or less than others.. mine charges £1.85 for packs (shakes or soups) and £2.20 for tetra's (ready made shakes)
you will most likely need 3 products per day if you are on SS (sole source) your starting point plan will be determined by your cambridge counsellor, some people are unsuitable for sole source.
checkout the cambridge weight management plan website for more information