Turn off data roaming, first and foremost.
Next thing depends on where you are going. You can get a Rogers SIM card for $15 per month that will give you 250MB. $35 takes you up to 1GB, I believe.
If you are heading to northern BC/Yukon don't bother with Rogers. They have no service up there. Your options are Telus, Bell and NorthWestTel. Have a look at their websites for coverage maps and rates.
For anything east of Saskatchewan, I'm in the dark.