Have you tried asking around?...When I was in Indy about 4 years ago I saw a couple in poor but usable condition for sub £150 at pawn shops, and I asked in Gander Mountain if the guys at the gun desk had seen any (I went prepared with an A4 photo of a BSA Standard)...Turned out one of the guys shopping there knew someone who knew someone etc. and later that week a guy brought in a Standard in good original order with some etching and a Quackenbush,he wanted 500 bucks the pair but sadly the Standard's chamber had a deep ding and the Quackenbush was not my sort of thing.
As I flew back I regretted not going ahead as he was open to offers, but my point is they were well advertised in the USA back in the days when they were made and there may be one closer than you think to you...You need to get some feelers out / maybe an advert in the paper etc. as you just never know.
I know it seems as if they are used as fenceposts here as once said, but good ones are getting hard to find and some of my best ones have been from totally "off the radar" places as when I was in "full collector frenzy" mode I would basically steer the conversation with anyone I met anywhere to the subject of old air rifles
So that means neighbours / work mates / any storekeeper with an antiques / flea type outlet / yard sales / small town auctions / even trade drivers to my workplace...all the previous have paid off over the years!
Happy hunting pal, it's the best part!
ATB, Ed