Have you checked out the HOP shop?? My first ever set of glowing poi came from HOP and I love them to death. I must admit there are other poi options out there that are somewhat better/brighter than the ones I got from HOP, but the rainbow ones are never quite as bright as single color. You can also buy them with the Foxy Socks which work very very well and have a nice bit of stretch to them without being too much.
The Hop Shop also sells Beaming Balls which are basically a hard plastic ball with 6 (I think) LEDs around the outside so no matter which angle you look at it you see an LED. They work well, but are a bit heavy if you are used to swinging glowsticks and they will hurt if you get hit. But hey, that's how it goes with poi. Personally I prefer heavy poi more akin to firepoi weight.
For other options there's tons of places out there. I'd HIGHLY recommend looking into buying a pair of Oggz.
http://www.flowtoys.com sells Oggz converted into poi but you can buy the straight up Oggz from the manufacturer and other various places without the loop in them so they can be dropped in a Sock. I have the Oggpoi from flowtoys and they are AWESOME, they are soft (cept for a small part at bottom) and colors are VERY VERY bright. Best of all, they are RECHARGEABLE which is a HUGE plus to me.
http://www.getoggz.com/ to get em straight from maker.
If you want to buy some different poi, flowtoys also sells its own Flowlights. They aren't balls but they are a REALLY GREAT glowstick replacement that runs off AAA batteries instead of super expensive button batteries. I have these also and they are great (the flowpoi duos and 2 flowstaffs as well). 10 modes, bright colors. Not too cheap to buy though but they are VERY hard to break and last a LONG time on 1 battery. I have been known to take the flowlights out of the poi they came with and drop them into socks to nice effect.
You can find glowing juggling balls at all kinds of sites and they are always a decent option though I would caution against any of the kind that have a bead filling in them as they always seem more dull than the regular plastic kind (prob due to the amount of material the light has to shine through)
But of course, Hyperlights are the end all be all of poi, but you may kill yourself with anticipation until they come out (i know i've died at least 3 times...)