Sunpower panels quote--reasonable? I've done a lot of research online, but it's really tough to fully understand what it should cost.

I've got a quote to install 5,886W DC of SunPower panels (18 of their 327W panels), and after a discount, it comes out to $3.66/W. How does this compare to what I might be able to get with a different panel manufacturer? The same installer offered SunEdison for $3.45/W. Located in Austin, TX.