I'm one of the mechanics at Bikeworks. We've been selling built-up bikes like crazy with the start of spring, so selection is a bit limited right now. It changes every week, so if she checks back a few times I'm sure we can find something for her. We have a bike building night every Tuesday, so Thursday night would be the best time to stop by (we're closed Wednesdays at the moment). If she's willing to do some work herself (with our guidance), that opens up more possibilities. Ready-to-go bikes tend to be around $80--$100, ones needing work are usually $40--$80.
As for other sources, there's a police auction on the first Saturday of each month. You could also keep an eye on Kijiji, which is much more popular than Craigslist around here. Most of it will be Canadian Tire specials, but decent bikes do come up once in a while. Value Village occasionally has something decent, but that's pretty rare in my experience.
Last edited by IanHelgesen; 05-12-11 at 11:00 AM.