I've researched this to no end b/c I'm sick of Telus and Rogers jamming us on data and minutes (and roaming charges in the U.S.).
Verizon is the only carrier to offer unlimited data (i.e. 5GB) and NO roaming fees in Canada for $70/month. It's called Globalemail:
http://www.verizonwireless.com/b2c/businessSolutions/global/pricingCoverage.jsp
You still need a voice plan.
Or you can get America's Choice for Business w/ unlimited data for $45/month plus .002 to roam in Canada. http://b2b.vzw.com/productsservices/wirelessemail/voicedatacallingplans.html
You need a voice plan on top.
They also have a Canada voice plan that gives various levels of minutes for ALL of N.A. without roaming charges. We live in B.C. and I just put my family on the Americas Choice w/ Canada Family version ($10 per additional line), for a total a lot less than Rogers was hosing us for.
I'll be adding the Pearl any day now. That will cost $10 for the voice and $70 for unlimited data w/o roaming charges.
What's interesting is that Verizon's partner, Telus, doesn't have a reciprocal plan. Using Verizon phones in Canada is cheaper than using Telus phones in the States.
I know this sounds like an advertisement, but competition is the only way to force Canadian carriers to lower their price points. Maybe they will "hear me now" if enough Canadians start switching service.