All diets are variations of kilojoule restriction (eating less than you need) with better nutrition. That's pretty much all there is to losing weight and getting healthier.
As for that blood type diet, it's based on bad science and assumptions, and has been pretty much discredited. I doubt a medical doctor would knowingly advocate one of their patients spending $700 for an unscientific and expensive approach over a standard "vegetables, fruit, grain and less processed food" approach.
There is no magic to losing weight, nor is there some special guru out there with secret dieting knowledge that is your only solution and is only available for money.
There are plenty of articles on the main website of this forum to explain what to eat, how much and when. Plenty of people have used them to lose weight. No one needs to spend more than $0 on a diet plan if they just take the time educate themselves.
Having said all that, Cooasie, I'm not saying a $700 or a $25 diet plan won't work for you, I'm just suggesting that there's no reason why a $0 diet plan wouldn't work just as well.
Striving to improve in every way possible.