Zipcar, Modo, I think Toronto has a lot of car co-ops. You can also join loyalty programs of rental companies like Avis. However, these won't build your no-claims bonus or insurance history.
Yes, I know Toronto's version of expensive insurance means "$500+". For academic purposes, I checked out my quote for Toronto online and it too came to around $500+, in BC I pay $200/month for an '04 Acura (still expensive in my opinion) - but that's quite a difference of almost $300 per month. I was told the reason for this is the high insurance claim value in Ontario, and probably the higher number of road accidents?
@ Emamabd - no claims insurance certificates from third world countries (do you mean Pakistan?) will count as well, as long as they can be verified back by the company.