I have received my allocation of 30 of the Smart Spark Energy BEQ-LA-5-100 battery balancers.
This is an active balancer that will keep 5 lead acid batteries in balance. As noted in numerous places keeping batteries in balance helps extend their life (or perhaps a better way of stating this is if you don't balance you will kill your batteries sooner).
The price is $219 plus shipping and handling.
I don't have the website up yet - I'm waiting for instruction manuals and warranty information. But if you want to buy one now drop me a line.
Customers who have already purchased an XM-3000 from me will receive a large discount. Future customers will also receive a large discount.
More information about the product can be found here: http://www.smartsparkenergy.com/BattEQ_for_Lead_Acid_Batteries.aspx (note that this site mentions a BEQ-LA-5-50, but that product is no longer available, the LA-5-100 is the model suitable for installing on an XM-3000, EVTA Z/R/20 etc.)