Maruzen P99 Threaded Outer Barrel

[Z Day Resistance]

I'm looking for a metal, threaded outer barrel and silencer kit to replace the non threaded ABS plastic one which comes stock with the GBB P99. The kit looks like this:

http://www.wgcshop.com/wgc2008/main/product_detail1.php?tabpage=1&item=MZ-SL-P99&search=searchItem&search_From=searchItem&rs=MaruzenGasPistols

The first four pages of google had only 'out of stock' sales, wondered if anyone new any more about them, whether they're still in production etc, any 'parts' shops I could try.

Thanks guys!