I have a 48mm LPS-P2 (Light Pollution Filter) filter for sale. It is the most advance light pollution filter currently in the market. Here are some technical details on this filter:
http://www.sciencecenter.net/hutech/idas/lps.htm
You are able to see some images taken with IDAS LPS P2 as my Luminance with the RC 14 on my Astrobin:
http://www.astrobin.com/users/ntk.thava/
It is currently going for $210 (shipment within Australia is included in this price)