I honestly don't know, except in online shops. Here's the official Power Grips website (i.e. the website of the company that makes Power Grips):
http://powergrips.mrpbike.com/fs_sea...p?search=grips
Here's some other websites:
http://www.universalcycles.com/shopp...ls.php?id=7045
http://www.bikemannetwork.com/biking/p/TS5001