You can get unlocked Pearls on howardforums for around 350........ there are a lot of great phones that use wifi and are unlocked. I use a N80 from Nokia and use the wifi with Voip for internet calls while on a wifi so no airtime charges. With Hydro having the downtown core covered and lots of free hotspots i do alright.
The other thing to look at are the O2 phones and iPaqs. The have wifi but also can use a skype client to do VoiP also. Skype calls are free anywhere in North America til the end of year and from my understanding this may carry over.
The unlocked Nokia E61 is a great phone and has the full qwerty keyboard and wifi.
check
www.howardforums.com lots of deals and lots of knowledge on their. Be prepared to pay but i found it worth it getting a unlocked uncrippled phone.