If you want to go low budget and play around there's lots of SBCs that can run Linux. Check here for example : https://www.armbian.com There's also ones that come as light weight keyboard, for example the pi400 Easy to carry around and put into a HDMI monitor. A drawback is that when using ARM there is sometimes software which only runs on amd64 family though that does not happen very often. Other option is to look at refurbished laptops. If you skip the chromebook ones (Which can be cumbersome to run plain Linux on unless you want to play with Linux and Android on top of ChromeOS) you can find them for 90 Euros or more.