A couple of years ago I was given a cheap Sunpak (I think it's a PF30x, but not positive - I don't have it nearby to look at.) The person who gave it to me picked it up on sale at Best Buy for $50. I don't use flash often, but it has worked well for me the times I have used it. Cycle time is long, it goes through battaries (AA's) quickly, and I'm sure there are other drawbacks compared to a good Canon flash, but for my purpose it has been fine.
BTW, I was using a Rebel XT when I first got it, but when I later got a 50d, the flash wouldn't work. I sent it Sunpak, they updated it for free and returned it within a week.