This unit:
http://www.xantrex.com/web/id/231/p/1/pt/30/product.asp...costs about $900 Canadian so in the area of $850 U.S. It contains everything needed for someone who does not want to sell the power back to the power company, just shave their own use. The total capacity is around 2.4KWh without the expansion packs. Using a 1/4th day charging period the approximate matching size of a solar PV array for it would be between 0.5kW and 1kW depending on your daytime loading differential. At $4 and change per peak watt, the associated panels cost between $2K and $4K. So we see that the cost of storage and electronics for off-grid and grid-backed PV (e.g. not "grid tied") is currently running at most 30% of the installed system cost, and more realistically given low nighttime power use, less than 20%.
Incidentally you can track charge controller, invertor, and battery costs at solarbuzz, not just solar prices.
In reality, solar does not need to be stored in it's major application: peak load shaving. It only needs to be stored if expected to satisfy the baseload. In which case, for the utility-scale storage consumers, we have beaconpower.com and the E-Stor ultra capacitors approaching market readiness, and for the residential storage consumer, products are starting to congeal into more "turnkey" solutions at affordable prices.