Stretch and Scratch are my favorite brand of cage scratchers, too. We also use the Humaniac Scratch Bricks (http://www.animal-care.com/product/humaniac-scratch-bricks/) which are nice because they're reversible, but they're not always the greatest quality-wise. Sometimes bricks will come with incompletely cut holes, or some bricks will have come apart into two pieces -- not huge deals, since you can easily just stick a screwdriver or something in the hole to get it punched the rest of the way through, and since the bricks are mounted with twist ties the tension keeps the two pieces of the scratcher together anyways. So they're still usable, just not the polished product you get from Stretch and Scratch.
After shipping, the prices are pretty similar for 50 bricks. Humaniac is only a couple dollars cheaper.