It's more aimed at honda's but it's a great site to read up on alarm installs. I'm in San Francisco, and alarm installs are range from for a basic install to 260 for a stealth install. It really depends on the shop. You should try shopping around, 300 seems a little steep.
I called and looked around today more. Everyone wants 250-300 in town. So I called my old installer (which is 3 hours away). Performance Audio Sound. They would do it for 200 including tax. Thats with a new siren and a LED Light, remote start and the smart windows. I just might do that. Plus Clifford will warranty the brain there. I just might do that.