First seen as the GGS Foldable ViewFinder, it looks like a number of businesses have rebranded this one. GGS is the company that designed the popular slip on LCD Glass screen Protector for the T2i. On it's first release the GGS Hoodeye view finder sold for over $120 dollars, but with all the competition on the market prices keep getting lower. This ViewFinder has 3x Optical Magnification, 3 elements in the optics and a +-3 diopter for the not so perfect vision. When not in use, the frame attached to the DSLR LCD is actually a screen protector (not just sticky frame).

Now on eBay the rebranded GGS HoodEye has fallen below $60 bucks, but this viewfinder is only available for square 3" DSLR LCDs. Found below.

3" LCD View Finder Loupe for DSLR

For those who are still looking for a T2i, T3i, or 60D (3:2 size LCDs), the CarrySpeedVfinder has dropped back down just a few bucks too.

CarrySpeed VFinder for Canon T2i, T3i, 60D and other 3:2 LCDs