I don't buy any 'diet products'. I'm pretty skeptical about their benefits and they always seem to be fairly expensive. I particularly don't buy into the 'meal replacement' shakes that so many diet programmes seem to love.
Eat healthily - meaning don't snack on junk, eat nutritionally good food, cook from fresh to ensure that you're not eating a lot of additives, control the size of portions and eat regularly throughout the day. I buy a lot of fresh fruit, veg, lean meat and oily fish. All of the bread in the house is wholegrain and we go through a lot of eggs.
I don't think you need to spend money on shakes and pills to lose weight healthily - just eat well and exercise.