any recommendations aon a manufacture or model? 
 
We use APC UPS here at work.  They are pretty decent.  The cheapest place I've been able to get them is Sams Club. 
http://www.samsclub.com/shopping/navigate.do?catg=535&item=328284&prDeTab=2#A
 
We haven't run any of the software (to automatically shutdown) on Linux though. Anyone have experience doing this?