I got something called Nitesiters. They're basically white stick on dots that glow in the dark, and they're AMAZING. They hold incredibly well and their glow is unreal. All you have to do is clean your gun, stick them on, gently heat the area with the new stickers to melt the adhesive on properly and there you've got it.
Check the site out.
www.nitesiters.com
I was looking for a cheap alternative and especially for GBB pistols' sights that have no dots this is the way to go. I was able to talk to the guy who created this item and he seemed legit enough for me to want to order them. Youtube has plenty a few great testimonials as well if you need a little more to go on.