If you are working on a budget, the Tippman 98 is the way to go. It's the AK47 of paintball. They are good, solid markers, simple, nearly indestructible, easily upgraded and have alot of mods and aftermarket support. If they are playing woodsball, it's the best option.
I have a 98 that is more than 10 years old and still running like a champ.
There is no reason to spend $750 per kid.