"Bloussant" and the other herbal supplements are indeed based on the herb fenugreek and do stimulate temporary (I repeat temporary) increase in breast size. The amount of breast size increase varies by individual girl. Most dancers who have tried these supplements have achieved 1/2 to 1 cup of increase after taking the pills for 3-6 months. The kicker is, of course, that the cost of the pills is like over $100 per month, and that as soon as you stop taking them the increased breast size starts to disappear. Since this and other herbal supplements are not really regulated or tested like drugs are, it is really not known if taking fenugreek on a long term basis has any undesireable side effects or carries any health risks. Of course the fact that herbs have been used for centuries is fairly reassuring, but on the other hand other herbal supplements like ephedra (used in herbal diet pills) has recently been found responsible for a number of untimely deaths.
My own position is that if you want bigger boobs, you'll want new boobs which are noticeably bigger i.e. 2, 3 or more cup sizes bigger instead of 1/2 to 1 cup size. This can only be achieved with breast implants. From a cost standpoint, getting implants costs about the same as five years worth of these pills, and after the five years your boobs won't shrink like they would if you stopped taking the pills!