I have about a dozen high performance kites. Not top of the line, but in the $200+ range. I have both two line, as well as quad-line kites. The quads are pretty awesome, you can control them laft to right as well as stop on a dime. It's pretty cool to see it flying down at the ground only to stop inches away. They don't really look like you expect a kite to look though.
I usually buy a new one while on vacation... but
www.intothewind.com is the place to buy. Their forum has been pretty good as well.