I agree with Jeff, allow your LD to have some (but not final) input on control system, as the best system in the world sucks if the operator can't work with it.
10% of your budget will probably be about right for a control system. I'm not a Lightjockey fan myself, and I have no experience with Chamsys, but I would avoid the "DJ" and entry-level packages if you go for software. The package offered by Megalite impressed me at NC&B, but I have no real-world experience with it. Bluelight was a disappointment, and the Elation and Chauvet programs just seemed too limited for a live venue.