Getting harder to find nowadays, but got an E mail of one off Flee bay. Might be of interest, it is the larger 500va model which is even better than the smaller ones.
Good hunting
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=230326703495&ssPageName=ADME:B:SS:GB:1123
Good hunting
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=230326703495&ssPageName=ADME:B:SS:GB:1123