I am going to buy the 3G Iphone but dont want a plan,(rogers) i want to have it as pay as you go,what do i do?

Apple introduced the 3G Iphone yesterday and its comming to canada on july 11th!! i am going to buy it but im sure it will have to come with a data plan because only rogers(or fido)will be selling them,I want to know if theres a way to buy the iphone, Take it home, and call rogers canada 1800 number to activate my sim card as pay as you go, Will this work? Do you know any better ideas?,