The key to weight loss and healthy shakes is to have comprehensive and absorbable nutrition in your shakes. Most cravings are because our nutritional needs aren't met, so we head for the cupboard but don't necessarily know what our bodies are lacking. (It's not all our fault - our food, even fresh and organic, is nutrient-deficient due to growing techniques, storage techniques, and eating food out of season that was picked 2 weeks ago on the other side of the world.)
The problem with most diet drinks and pills is that they stimulate the central nervous system. They don't necessarily meet your nutritional needs. You can get a quick weight loss but it's hard to sustain, and you don't know what damage you are doing inside. For example, weight loss occurs when muscle tone is lost (and muscle weighs more than fat) - it looks good when you step on the scale, but is it beneficial? No. We all (and especially women) need more muscle and we need to do weight-bearing exercises to prevent things like osteoporosis.
If I were going to spend $100 on a supplement, I'd make sure it was making up for food I'm not consuming, that it was nutrient-laden in a way that survives digestion (doesn't matter what I swallow, it matters what I absorb), and that it was 90% or more absorbable directly into the cells. I'd also question what a "shape kit" is - is it all product, or is it a pamphlet that tells you to walk more and park further from the supermarket entrance? Well, duh!
I'd also look into whether this product has warning labels required by the FDA. If it's entirely food based, then it won't be FDA approved (no food is) but its ingredients should all be on the GRAS list (Generally Recognized As Safe).
If you're going to be adding whey protein, you're looking at an added expense anyway. So how are you evaluating the whey? Again, I'd go for something with proven health benefits for immune system support and anti-inflammation, not just something that boosts metabolism. I'd look for patents (very hard to get on food products and a sign that the company has invested in science and purity as well as a unique and proven-safe formulation).
Yes, you can make your own with natural peanut butter and some plain cocoa (very low calorie) and some kind of liquid base (a lot of people use almond or coconut milk), but are you going to stick with it? Even if you do, how are you guaranteeing that you are meeting your nutritional needs?
I've done the approach I recommended and have found much better results than trying to play kitchen chemist myself and mix the right proportions. Added to this is the recent work in a natural superfood that helps with inflammation, cholesterol reduction and appetite suppression (there's a certain amount of a natural peptide that affects your feeling of being satisfied/full). That's how I educate people, and because of heavy use of clinical data in the formulations, we're seeing phenomenal results as well as 60+ scientific papers on the health benefits, with complete safety.