Let's review...

The first priority is to reduce wasted energy by using energy efficiently. Complete all of the low to no cost energy improvements in your building. This will reduce the required size and cost of your solar system proportionately with how much energy you save through efficiency.

The second priority is to be knowledgeable about solar. I have a clear view of the Southern sky with no shading and know what solar can do for me and my building.

Step 3 is to click here to go to Sharp Solar's website to have someone contact you about a proposal for Solar for your building.

HB Surf & Sun - Get Solar locally!

If you aren't interested in the HB Hometown Solar rebate but still want solar, go here to see installers that are qualified by the California Solar Initiative.

How do I know what a fair price is? It varies with multiple factors depending on your roof and electrical system but scientists at Lawrence Berkeley National Lab studied installed costs of solar and their results can be seen in the graph below.

Most residential systems fit into the first 2 columns and are expressed in dollars per watt.

From the LBNL study Tracking the Sun: The Installed Cost of Photovoltaics in the US from 1998-2007

Additionally, Go Solar California has rough estimates of cost per watt available here.