For prepaid, you can look to SpeakOut wireless. $10/mo for unlimited data. However, I'm not sure if you can tether.
You also just can't buy a SIM card from SpeakOut. You need to purchase their hardware, take out their SIM card, and re-sell the hardware via CL. Not difficult as there are multiple promotions during the year and their hardware works perfectly with Rogers SIMs without unlocking. Just a bit of work.