Where can I get cheap fabric?

I'm just starting out with sewing and I get a little frustrated when buying fabric. I'm a knitter and I know where to get cheap yarn online and can see a good bargain when shopping at my local yarn shops but I feel so lost with fabric. I'm afraid of paying too much and then ruining it with my noob skills.

Are there any websites that sell really cheap fabric? I live in Canada so it would be nice if they ship here.

Also, if anyone lives in Toronto, can you tell me where I can buy cheap fabric in the city?