When you disable logging, all that remains is:
- HDD size (I tweaked my install to fit inside a 2gb hdd, see some other thread i made)
- RAM (256mb minimum, non-oversold)(so go with a kvm or xen vps)
- CPU
As you want to host for 20-30 players, cpu becomes an issue. Most vps providers dont take too kindly to people maxxing out a full core, and youll be looking at 50-100% of a full core. If you can find a cheap i3-based dedicated server, that would probably be better. (or try to find a vps host that allows you to use a full core, but that mostly means that others are also allowed to use a full core, making the node perform like shit)