We have 4 of these batteries that were used for a year in a client system.  
They have now expanded their bank, we have these available. 
Lightly used, very clean, kept in a heated building.  
$2,250 each, or take all 4 for $8,000.
 
These are a high-quality, US made, Lithium battery. 
Unfortunately they don't have 2-way communication with the new inverters.
That said, they will work with any inverter, they just require a bit of programming to get good state-of-charge information.