Orlistat is still under patent so technically at the 120mg dose there can as yet have no cheap generic. That dose is also prescription only, so statistically whether you buy it off perscription there is an 85 chance it is non-genuine.
Alli is 60mgs of orlistat and can be bought over the counter. Though In controlled studies orlistat performs fairly well, of course the prescribed dose is twice the over the counter dose. Notwithstanding in the community, like most diet pills it does quite poorly, in fact 2 in 3 pill dieters actually end up heavier!
Unfortunately to receive anywhere with orlistat you have to be on an ultra low fat, low calorie diet and take exercise. Even then it can produce wind, stomach cramps, foul smelling orange liquid diarrhoea, which sometimes does not make it as far as the loo!
try drugstore.com or boots.com
you can go to the canadian websites i just don't know if the website is reliable but it's not too much of a difference in price at least not worth the risk