I usually order from AirsoftParts but like you said, it's out of stock. eHobby and quite a few others are out too but WGC has some left -->
http://www.wgcshop.com/wgc2008/main/...rchItem&rs=pgc glock&catid=&cat=
You shoudn't have any problems with customs and it's a great slide btw.
