From the game! I love that thing and it's permanentness.
dont know where you can get them
but i know they are cheap
Fishermen's shops often sell them as baits.
Also camping stores might have some to offer.
Menards sells glowsticks.
I used them when I was in the army. I guess you can find it your average "army-shop" that has cammo-paint and stuff.
Be carefull, there two kind of lightsticks, the Cyalume is "one use" and last 12h with the glow of a candle, the other one is the glowstick from Penumbra and last 10 years, but glow less.
You can buy both on eBay.
lol i wanna have the one that last 10 years :p
but you dont have to go to ebay specialy for that :p