Tom, something to keep in mind; parts are more expensive than colt parts, and onc eyou start to build one up, it usually costs more than if you bought a joe blow shooter.
Luger Doc here on teh forum has most parts.
A bunch of early 1906 parts were for sale on ebay last night.
Auction arms has a guy named XXXXX XXXXXXX (my mind is blank, he insists on no pictures, but by gum can find any numbered part you need, so rumours are that he restamps them). No one I know has been happy with buying from him. Gunbroker has lots of parts.
I myself have enough parts to build 2 lugers plus, some of the parts I have are 1's and 2's and others I have 10-15 of
but no matter what, you're will pay more this way than buying a shooter.
Advantage to putting together parts is that you can buy some here or there cheaper, than buy a few more later and it doesn't "seem" as expensive...
A nickle plated or chromed is not that easy to take the chrome or nickle off, or folks would do it....
Welcome to the forum!
Ed