Some experience for assistance.
Most senior collectors do not use CL or Ebay as a primary source, especially for rare games.

In priority order:

1) Private collectors - Individual connections (best option, keeps games with the "right" people)
2 ) Facebook - Closed collector groups (generally much more easy to get like minded people, and not just "flippers")
3 ) Private websites - Local collectors only, not forums (removes "flippers" entirely from the picture)
4 ) Dealer websites - Consignment sales (Keeps the "junk out of the trunk", but you will lose some profit)
5 ) PinSide (or other forums) - General collectors (More like minded individuals, but not necessarily knowledgable)
6 ) RGP - General collectors (Will get serious offers)
7 ) Mr Pinball - General collectors (can be a complete crapshoot now)
8 ) Ebay (or seller "stores") - General public (ad fees are wasteful)
9 ) CL - General public (by far the "worst" of all options, "flippers" are rampant and you will be wading through the cockroaches of society)

I start from the top of the list, if sales only, not for trades.
These are the most common, but there are more, dependent on needs.

If I had to calculate the highest % method of the 600+ games I have bought and sold, it would be #3 (private websites) at nearly 35%, followed by #1 (private collectors) at 20%. This is only because Facebook is a "new medium" that has really only come about in less than the past 10 years.

Only in my early days did I ever really buy anything from Ebay or CL, and only a handful overall. People are really rolling the dice with Ebay, because I nearly always politely ask for additional clear photos (as the ones on ads are crap), and the the response is usually resentful or why? This is especially true for bottom side of PFs or board sets.

Yes, a rebutted and contested PayPal sale agreement, and your funds being held or frozen in your account for weeks.
The hassle can be unbelievable, and their customer service is complete a$$.
The buyer can put you at the mercy of a system that not only is in their favor, but is also convoluted and mistake prone.
Private owners (and even dealers) should not use PayPal as a means of payment, if avoidable.
vid1900 wrote an entire PinSide thread article on Paypal, and it is exceptionally concise and accurate.
We are not talking about a couple hundred dollars usually here, and it is not based entirely on "scammers".
There are problems using this as a sales medium of sale for private ownership direction.

Conduct "cash and carry" as-is sales or a direct wire transfer as the primary method of sales.
For the holy sake of pinball, make sure you create a proper SALES INVOICE for any game you sell, with signatures of both you and the buyer in duplicate, and witness if the transaction is ABOVE $10K.
Go online and download the fillable pdf forms, they are FREE.
Nobody seems to do this any more, but the buyer will thank you too.
You will thank yourself when the buyer has "remorse" and wants a refund.
People are fickle, and you only need to look at the website to see the examples.
Money orders or certified cashier checks for large amounts is suspect, as are other means.

Here is a free invoice online creator that also works great:
https://invoice-generator.com/#/1

Keep flipping.

There are multiple closed group pages, all generated by individuals for regions and types of collectors. Do a keyword search, such as "pinball sale "

Denis Warobiew is an honest dealer.
Pinball Universe has grown quite bit since its early days nearly 30 years ago, from the "mom and pop" period in Colorado as an exclusive side business.
Another of the businesses that did heavy reimportation of games from Europe back in the 2000s.
Those were a different time in the hobby.
His crew is fairly small though, and all his techs except one are college age for techs with limited experience outside late and modern pinball machines.
You do get what you pay for as long as you know what you want, and what to looking for overall.
He is not going to shyster you, if you are looking for something high end as a collector.
I may have bought 8 machines or so from him in 25 years, and sometimes he even has some really special gold nuggets from collector buy outs.
I still peruse the website periodically.

"Know you games, your prices, and conditions of what to look for in a game title. You are the researcher, not the seller."
- TBK