You could have a look on www.gunbroker.com it's a US based site and there's usually quite a few on there. You need to register, but it's free, I've just got some Hawken parts from there and there's also usually a few on fleabay US, tha's where I got my Hawken stock from (complete with all of the brass fittings and set triggers £29.00 + £10.50 p+p) and I've just got a lock from an aquaintence in the States, for less than £20.00 posted.
So they're out there
ATB
Baz