Blacked-Out Rear Sights are becoming more popular for all applications from military to competition. These rear sights are available for all GLOCK models. I found this excellent article to explain help more about this type of sight here
LumiDot Orange Front Sight $24.99
LumiDot Orange Dot Front Sights are great for dim to brightly lit areas, easy to pick up and quick to acquire. Available for all GLOCK models.
Steel 3 Dot Sights 9mm/40 cal $49.99
Steel 3 Dot Sights 10mm/45 cal $49.99
AmeriGlo Steel 3 Dot Sights are available in plain white and glow-in-the-dark varieties.