Getting a iPhone on a prepaid/monthly plan?

I bought a used iPhone for $200 (she hasn't used it for a while, it's been in her closet) and i was wondering how much a monthly plan is for the iPhone 4. I currently have bad credit history from the past but my life is on track now and i would be able to keep up with it monthly. I live in Saskatchewan, Canada and i wanna go on Sasktel 3G. Anyone know how much?

Make it simple for yourself, just buy a prepaid SIM card and stick it in. You could pay as little as $ 10/mo. The sky is the limit if you "go for it all", upwards of $ 120/month.