Lightly used...no. But Adam Webber has them new in box, in stock and ready to roll...no comment on the price which has escalated sharply in the last few years:
http://www.hkparts.net/shop/pc/HK-German-PSG-1-Rear-Stock-Complete-197p531.htm
Aside from that, maybe try HKPro and the forums there. They come up for sale sometimes and usually go fast. A WTB post there might help you out too.
Good luck! [/quote
Tried them but they are not answering the phone.