I like looking here as a start for PV pricing:
http://www.ecobusinesslinks.com/solar_panels.htm
(although that site really is more paid advertising rather than an unbiased survey of all online vendors)

Keep in mind that all your components (panels, inverters, racks, cabling, breakers, etc) need to meet UL standards for a grid-tie system, and your design and installation will need to meet the standards of your local utility company, electrical inspectors, home insurance provider, and city building department inspectors. Start with them to find out what is needed in your jurisdiction.

Also keep in mind that depending on what subsidies are offered by your utility co and state/city, it may or may not be more cost effective to consider solar thermal panels for your domestic hot water system rather than solar pv.

I'd also recommend you do some reading on the NAWS forums at http://www.wind-sun.com

I am currently taking data on three different PV systems from three different manufacturers, but all installed by the same company, in my area so that I can do some comparisons. It is too early in the process to come to hared conclusions. One preliminary observation is that all three systems seem to perform similarly when normalized by their rated power, that is, the energy collected over a month divided by their rated power is similar. The rated efficiencies vary, so that high efficiency panels can collect the same energy over a smaller area, but there may be a small price premium for that higher efficiency. If space to mount the panels is not limiting to the size system desired, then it might be possible to save some money by using lower efficiency panels over a larger area. On the other hand, is space is limiting to the size system desired, then go with the higher efficiency panels.

All the panels seem to be converging on a guaranteed performance standard for 90% of rated power at 10 years and 80% at 25 years. I assume that must be a standard set by some organization in the industry.

Unless you are going to piece together a system and install it yourself, it seems like you should be talking to installers in your area. You shoudl also talk with the state energy agency about what rebates or subsidies are available for solar PV systems.