You'll find them readily available on Ebay, but there are also multiple companies that specialize in refurbishing servers (which usually will allow you to configure your actual needs - but this will be slightly more expensive in my experience).
Someone just moving decommissioned servers from a data center to new users without doing anything with the equipment in between allows you to find decent deals if you're looking for something to put in a rack.
Be aware that rack servers are usually rather power hungry, so they might be expensive to run over time.
Someone just moving decommissioned servers from a data center to new users without doing anything with the equipment in between allows you to find decent deals if you're looking for something to put in a rack.
Be aware that rack servers are usually rather power hungry, so they might be expensive to run over time.