There's no real outlet for them. I think Arlington Ordnance may have some that they've refurbed. Expect to pay big bucks for any of them. I'd say the best bet would be to haunt the gunshows, auction sites, and maybe reenactor or collector types.
I bought mine from a collector. He had a bunch of them and knew a guy that had one that wanted to get rid of it. I already had a ZF-4 scope that some GI brought back from WWII and gave to my dad. I bought a repro scope mount (Sarco type) from another collector. It shoots good, and is a fun rifle.
You may want to stick to earlier production. Slave labor and all may make the later ones dangerous. I would do some research on it before buying. Mine was made in early 44 by Walther and was supposedly safe according to all the gurus.
All I can say it that mine shoots tight and is a blast at the range. It's a damn good gun. Get one if you can.
A gun shop had one up here about a year ago. Last I heard he was going to sell it in the states where he could get more money for it.
I will check and see if he finally got rid of it.