I will add one more possible excellent source if you're in no rush, though to some this might be a bit morbid. But hey, it's Halloween.
As people downsize or die, the contents of their homes are often put up for auction and very good older equipment can be had for extremely good prices. This commonly includes older stereo equipment including the very receiver William needs. I've seen old models of high-end brands such as Marantz and Denon go for next to nothing because they're all-analogue. (Sometimes retailers will use this tactic to get rid of thought-unsellable inventory so there are some "reseller managed" auctions in the mix.)
(BTW, I recall Sanyo as a mid-tier brand in the 70s -- I'd say the current equivalent in computers would be Acer.)
The best estate-auction site of which I'm aware is Maxsold, which both manages auctions and promotes seller-managed ones. You tell it where you live, what you want and what distance you're prepared to go to pick it up, and it finds all relevant auctions.
Here is the first thing I found when looking: receiver, equalizer and multi-disc CD player sold as one lot (you have to buy them together). Current bid is $1 and closes in six days; if you have the winning bid you have to pick it up at a specific place and date. Much of the stuff sold like this is as-is, but usually the owner will report if it's in working condition. Auctions usually last for a week or two but there are new ones all the time.
Most people who want to sell stuff like this while they're alive will use sites like Kijiji, Facebook marketplace or even eBay. But Maxsold also makes sense if you have a lot of stuff to get rid of after spring cleaning, it will bring more money than a yard sale.
TMI time: In another message Hugh wrote:
New receivers often don't support RIAA equalization needed for record players. You can get an external phonograph pre-amp to do that or you can get an old receiver with a phono input.
(Since phonographs are cool again MAYBE phono in has been revived on some models.)
In my experience (and my first job was at a stereo store, TAT near Yonge-Steeles), a pre-amp might be necessary, but it has nothing to do with equalization. Rather, there used to be two stylus-cartridge types used for turntables -- ceramic and magnetic. Ceramic cartridges were cheaper and had lower-quality sound, but produced high sound levels similar to other sources like cassette or CD players. Magnetic cartridges were more expensive and accurate, but far quieter and needed a pre-amp. Most receivers made from the 70s to the 2000s. and many but not all made today, have a separate "phono" input that indicates a pre-amp is built in. Given that these days vinyl records are bought for perceived better fidelity, ceramic-based cartridges aren't even made anymore; the difference now is moving-magnet or moving-coil. And I just shocked myself seeing what can be spent on just a cartridge these days, in support of a medium I thought was obsolete.
(Whether the "record player" William has is ceramic or magnetic depends on the stylus cartridge installed, not the turntable itself. Most likely magnetic.)
HTH,
Evan