Check this games website out!

Nothing beats owning a physical game.

https://retrogamesexchange.com/

Has a growing library dedicated to the buying and selling of retro games. If you are looking to make a purchase or have some old games you want to sell. Get in touch with them. I am not affiliated with them in any way. I've just been following the site for awhile and it looks like a great idea. The website is really well laid out aswell. I might even try sell a few games on there down the track. Check them out!