Why is it whenever somebody posts a specific question about a specific product, three or four pimps chime in recommending whatever competitive product they're pimping?
(just wait, I'm sure you'll get plenty of responses regarding cabrinah, naish best, and some of the others)
As far as Gaastra, I bought an 04 GXR 16.5 new off of ebay last winter and it was great in low-wind conditions, but it had terrible jellyfishing whenever I needed trim strap pulled in more than about 1/2 way.
With the newer kites, I don't know if they fixed this problem or not but it kind of put me off Gaastra (and tube kites in general as it was my first LEI).
Hey what you really need for your school is some Anomaly kiteboards - they're... uh... Pimpin!