FYI there are shortages for batteries typically used in Alarms and UPS's etc from most if not all mfg. If you do locate an ELK-1280 battery make sure you ask the date code on the battery before you buy it. I found someone (locally) selling batteries that were over a year old and asking for a premium price. I instead went with an ADT branded battery mfg by KJK in China that was only 4 months old (but a 7 aHR not an 8 aHR).
The problems seem to be a change in regulations in China for the proper handling of the lead used in the batteries.
I can't say I've seen any change in the availability in batteries, and we're buying approximately 500 SLA's a month for a single site, let alone our other sites, and I've yet to see any out of date code issues....maybe you have a supplier issue.
HDD's for PC's, DVR's and NVR's on the other hand...huge shortages and cost increases.
I agree with the posts above, the battery, while it may have a "float life" of 10 years listed, a deep discharge most likely caused damage and wouldn't be worth the issues it'd cause on a panel compared to the price of replacement.