Varhar: Unfortunately there are no easy ways to locate parts for your pistol that haven't been made in decades. Rest assured though that the parts you are looking for are out there probably stuffed away in some forgotten place in a work room, or drawer. Put out as many "feelers" as you can on different firearms websites as you can and don't forget to go to as many gun shows as possible. You would be surprised how many times I have found items I needed looking for something else at a gun show. A lot of early Model 52 owners bought extra extractors because the word was out they were prone to breakage, or so it was claimed, so they bought spares. Truth is almost any extractor can break so why not have an extra.
Remember too that not all gun shows are equal. There are the average run of the mill gun show where they sell more non-firearms junk than anything else and then there are the really good shows where you can find almost anything. Every couple of years I try to go to the big shows with a list of items I need. It's hard not to get side tracked at the big shows, so I try to look for what I really want first and then I browse afterwards. If a vendor looks like a good candidate I give him a card with my name and contact info on it with a short list of what I need and ask him to let me know if he runs across the items on my list.
I never owned an early Model 52 so I never felt a need to buy a spare extractor for one, but I do see them occasionally. I also get on the Fleabay watch list for items I need and that has worked a few times for me, but you have to be Johnnie-On-The-Spot when they send you a notification on something. Keep knocking on doors and become a detective of sorts. It may take a while, but your needed/wanted part will show up. As a side note to this, I was just in at a local Mom and Pop gun store buying a Trijicon SRO optic. The owner remembered me from a earlier run-in and he said he found something for me and handed me a Model 52 magazine with a metal follower and asked if I still wanted one. I said sure and asked how much? He thought for a minute and said 50 bucks and I said sold! He found it in a kitchen junk drawer of all places. I didn't haggle or try to buy it cheaper I just bought it at his price. Things do pop up when you least expect them to. Good Luck!
Rick H.