I bought a decent video camera about 5 years ago for my school and haven’t used more than half a dozen times, mostly for videoing our winter concert and during COVID times. For schools, I don’t think we have to make huge investments – we’re making videos for YouTube or Social Media, not Hollywood.
I think most mid-range phones will do the job nicely – I think you’d even get away with not bothering with a SIM card and simply point-click-upload to a YouTube channel or wherever, and that will only cost you the price of the phone itself. I’m pretty sure you could get the phone for under €200 in any decent computer shop. There are a lot of small independent electronic shops with second-hand devices, and they’d do the job too.
Having said that, for not much more, you can get a basic camcorder with wifi capability. Try your local Currys, Harvey Norman or DID and you never know what kind of deal you’ll get for a couple of hundred euro.
If you want to go down the route of getting the kids to video, there are some cheap and cheerful options for <€100 here: https://www.amazon.co.uk/video-camera-kids/s?k=video+camera+for+kids but I can’t vouch for any of them.
For me, the main points to consider are what you want to use it for (none of the above will be much good for a concert) and whether your footage can be uploaded directly from the camera to the Internet.