I've been really interested in purchasing an off-camera flash, as the on camera flash is becoming increasingly irritating. I have a Canon Xsi, and all i've really seen from canon is their speedlite series, which is very pricey imo. Are there other options, other than the canon speedlites? I dont need a high-end flash, because im just a beginner, but i would like something that would give me better results. thanks!