So if I get a paygo SIM from ebay (current cost about $7) and a $100 top-up from PetroCan/7-11...
Not quite, since;
1) You can't activate the Rogers SIM on 7-11 or PetroCan service.
2) To get the 7-11 or PetroCan SIM you have to buy the phone+SIM combo.
Check the web, but I think the current cheapest (7-11, or PetroCan) phone is about $60, but once in a while they run promotions giving you the phone for free if you sign up for a $100 top-up card. Worst case is that 7-11 or PetroCan would cost you about $160 for the first year and $100 thereafter (assuming you don't need more airtime). Both plans use the Rogers network but do not allow US roaming.
On the other hand, assming you don't need/want a new phone, you could get a Rogers SIM from eBay and just activate w/ their Paygo service. In this case your first year is $107 (assuming $7 SIM) and $100 thereafter (assuming you don't need more airtime).
Advantage of the Rogers-direct option is US roaming, since you want occasional vacation use and online customer support & top-ups. However, there's a premium @ 25cents/min vs. 20cents on the 7-11 and PetroCan reseller (or MVNO) plans.
For more info on the 7-11 Speakout service, check this site; http://www.speakoutwireless.ca/
For more info on Petro Canada service, check this site;http://retail.petro-canada.ca/en/mobility/2303.aspx
For more info on the Rogers paygo service, check this site; http://www.rogers.com/web/content/wi...paygo_overview