If they offer an "all-inclusive" price, read the fine print. It will almost definitely not include:
The flight to the USA
TSA fees, VISA fees, medical fees
Meals
CAA license issue fees
And possibly the price is quoted for a basic package including 45 hours C152. If you want to fly a different aircraft, if you overrun the three weeks accomodation, if you overrun the 45 hours, if you require extra ground tuition, or fail the first pass at each exam, you'll probably have to pay extra anyway.
On the other hand the package may include a pilots bag filled with stuff that can be bought cheaper elsewhere, or is not needed anyway (like two rulers and three protractors).
So a pay-as-you-go scheme may well work out to be cheaper in the end.