If you want something small and cheap, it might be worth getting a used thin client PC.
I got a cheap £20 Igel thin client from eBay as raspberry pi’s were still far too expensive, plus I already had a spare 4GB ddr3 sodimm to drop into it and a 120gb wd green ssd that I’d stripped from its case and fitted internally into the thin client.
After upgrading it one ended up with a 1.2ghz AMD GX-412 cpu, 4gb DDR3, 120gb sata ssd and an external usb 3 1tb hard drive i also had laying around.
As a component of my homelab, it’s running Debian 12, docker with a few containers (pigallery 2, Libreddit, portainer, searXNG), it’s my backup Emby server and my main Pihole and PiVPN client.
Completely silent, sips power and still has capacity spare to run more containers and other projects that catch my interest.
Working really great for me. I originally just bought it to run Pihole on a dedicated machine and have a secondary pihole instance on my Unraid server in case either of them went down but leaving it sitting there with just PiVPN and Pihole duties seemed wasteful.
I’m getting even more out of it running some of the lighter containers on it with plenty of spare room to do more.
I’ve logged/uploaded my upgrade process here just so you can get some ideas on what I did.
https://imgur.com/a/ExcLdtt
It is bulkier than a raspberry pi, being around the size of a router but the low cost and being able to utilise hardware that I had sitting doing nothing made me go this route rather than just getting a pi.