The Japanese-made IDAS P2 LPS is the BEST Light Pollution Suppression filter for astro photography with DSLR, colour and mono CCD cameras.
I have the 2" version which you can use in front of your optical trend to block off light pollution for your imaging. I have taken many images using it (
https://www.astrobin.com/users/ntk.thava/). Now I have a 36mm IDAS LPS P2 in my filter wheel for my Luminance and so I do not need the 2" one.
You can read more about it here:
http://www.sciencecenter.net/hutech/idas/lps.htm
http://www.iankingimaging.com/show_product.php?id=1560
It is for sale at AUD 220 (shipment all included for anywhere in Australia).
If you are interested, please call me at 0428727976 or email me at
ntk.thava@gmail.com
Cheers and clear skies !