In general, almost every "bright" lens under f2.8 will be surrounding the $1,000 mark.
There are some remarkable deals though, such as these f1.8 50mm lenses that go for about $100. They work both with full-frame sensor cameras as well as with APS-C cameras.
For the first ones, these would act like "normal" field of view, for the APS-C Canon Rebel, 50D or the Nikon D40, 60, 70, 80, 90, 300, 3000 and 5000 these will act as a short telephoto, very suitable for portraits.
For your Canon: