It depends on your needs for reliability and how many users you have.
If you don't mind being offline when doing maintenance occasionally and being down on the rare occasion when the hardware fails (like once in a few years) until you get the replacement part, then look up "server housing". You can buy a computer, either rack mounted, or tower, maybe used, and you put it into a datacenter that manages bandwidth, power and cooling.
That would be probably the cheapest option but pick something close to where you live.
If you don't mind being offline when doing maintenance occasionally and being down on the rare occasion when the hardware fails (like once in a few years) until you get the replacement part, then look up "server housing". You can buy a computer, either rack mounted, or tower, maybe used, and you put it into a datacenter that manages bandwidth, power and cooling.
That would be probably the cheapest option but pick something close to where you live.