you may also want to look into
www.easyclosets.com As I recall, they were less expensive than California Closets.
you enter your closet dimensions online, and can build the unit with different configurations.
think you can choose to do the assembly yourself, or pay for installation. My husband installed this system in my daughters room--numerous drawers and shelves in our configuration--took a full day to install it.
However, I'm quite pleased the the product. It has held up well (going on 5 years old now) under her wear and tear.