ETS is coming up with translucent magazines for Glocks. Currently, 9mm 31, 22, and 14 round magazines are about to be available. In the future, there will be other capacities(15 for Glock 19 and 10 round magazines for ban states)
http://www.etsgroup.us/ETS-Group-Glock-Magazines-s/1823.htm
Price is $21.99 for 31 and 22 round magazine, $16.99 for 17 round magazine
From: ETS via The Firearm Blog