I'm looking for a server provider who will sell me a server with 200 slots. Price should go up to 150 euro
Monthly? Oha, for this money you can rent a dedicated server with 128GB RAM and a powerful server processor and still have money left over. The beast will also pack more than 200 slots.
150 euro?
Just rent a dedicated server e.g. At Hetzner.
https://www.hetzner.com/dedicated-rootserver/matrix-ex
or
https://www.hetzner.com/dedicated-rootserver/matrix-ax
Are cheaper and can set as many slots as you want.
Are they reliable too?
I have a server at Hetzner myself.
Spending 150 euro per month on a Minecraft server is a huge waste of money because a root server from Ubuntu or Netcup with 2 cores and 160 GB is completely sufficient for two Minecraft servers:
https://www.netcup.de/vserver/
Only it doesn't have 200 slots -.
This one asked the exact same question