Yes you can buy a prepay phone and then assign it to your month-month account (although there may be a grace period). You can also take a look in places like the local newspaper classifieds, Craigslist or e-bay; you can often find phones that are for sale on there. Just make sure you get the
ESN from the seller and check it with Telus (contract issues, stolen phone, etc.) before buying it.
Hope this helps.