I have had the top-spec model since 2020 and use it very heavily running Windows GIS software in a 32gb VM, rendering/exporting maps 24/7 for weeks at a time frequently. Quite a workhorse for me and the integration with MacOS on Parallels is a huge plus.
This was posted awhile ago on MacRumors and I see they are still available, very tempting if you want a 2018 Mini. 32gb hex-core i7 for $269, claims to be factory-sealed new in box.
BRAND NEW FACTORY SEALED --- Apple Mac mini (Late 2018) Core i7 3.2GHz 6-core 8th Gen, 32GB RAM, 128GB PCIe SSD, Wi-Fi + Bluetooth, MacOS Mojave 10.14.1 - Space Gray
www.amazon.com
The "gotcha" is the tiny internal 128gb SSD but probably not an issue for a media server with content on an external disk. Of course, $269 USD is like $369 CAD, so it's no cheaper than the ones you have been looking at, but at least it's new.
I was using a 2014 Mini as a media server and replaced it with a base m4 Mini here however. For me, that was a better solution and will be supported much longer by Apple. Today, I think the main appeal of the 2018 Mini will be Windows compatibility - also Mojave compatibility for old MacOS apps I guess.