Rent A Wreck info page is rather helpful and includes these
Usually, Rent-A-Wreck requires renters to be at least 18 years old, but some locations may require a minimum age of 25 years. For consumers under 25, a credit card is usually required for payment and the rental rate may be higher. Please contact the individual Rent-A-Wreck car rental location for their specific age policies.
Many, but not all, Rent-A-Wreck locations will rent to cash customers. Most locations will require that cash customers fill out a cash qualification questionnaire at the rental location during normal business hours so that it may be verified. A cash deposit will be required if a credit card is not presented for payment. If you are interested in renting a car using cash, please contact the individual location for their specific prices and policies.
Debit cards or 'check cards' carrying the logo of a major bank processor like VISA or MasterCard that are linked to checking accounts are also accepted as a form of payment at most Rent-A-Wreck locations.
In Canada they redirect to http://practicar.ca which have many, many Toronto locations. Good luck!