$850 is way over what these are worth in my opinion. For just a few dollars more you can buy a really decent Luger.
Even an asking price of $650 would be pushing it for me..It's a frankenstein mix of parts and might not even shoot.
Take a look at this one in the for sale section on this Forum.
http://forum.lugerforum.com/showthread.php?t=23775
Jerry Burney