ask dr "canadian cellphone" LJ

So, I'm planning to go to worldcon. It's in canada. I have an ATT networked non-jail-broken iPhone with a fairly boring cellphone-plus-iphone-data plan.

What's the most affordable way for me to use my phone in Canada? Should I just turn the thing off at the border to avoid getting hit with huge fees and go cellphoneless? Should I get some kind of Canadian prepaid rental phone (if there is such a thing)?

I'd like to at least have basic cellphone capability, although full-on data would be great to have as well.

thoughts?