Extensive discussion on Cruisers forum:

http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-84.html

Lightly used (test ?) older (2-3yrs) discount (-40%) cells are available here:

http://www.balqon.com/store.php#!/~/category/id=4218089&offset=0&sort=priceAsc

260AHA and 400AHA seem to be sold out, but there are plenty of the larger ones available.
The regular prices continue to fall as well.

I bought a set of 4 * 400AHA and so far they seem to be great.

Cheers,
JM