While Roger is absolutely correct about accuracy and quality, the trimmer by "Carl" is adequate for light duty. Although sold by Freestyle, it's also available at Staples, and Office Max and the like. It's still about $50 American for one that will trim an 11x14 print, but that's a helluvalot less than the several hundred for a Rotatrim. Also, you can get replacement cutting wheels and cutting wheel 'beds' at office supply stores.
It takes more care and effort (alignment and holddown of the print), but as I only do a few prints at a time, it's worked out well for me. (I also suggest that drinking Scotch while using the trimmer is not the best way to proceed.)