I use The Courier Company when I need to send a same-day package within the GTA. If you have an account, they'll bill you. If you don't have an account, you can pay on credit card or use cash. I've used them a bunch of times and have been satisfied every time.
I use the Courier Company with one of the production companies I work with. They have an account but I am pretty sure they would love your business if you don't need an account. Plus they are good and offer bike or car service - quick or slow.