Add to that rackspace costs, staff time doing installation (or cost of remote hands etc). I don't have our figures for rackspace costs, but staff time is fairly low — an hour or two when the server is purchased and later thrown out, and maybe the same to replace a HDD at some point in the 5-8 years we keep it.
Also add the time to get competing quotes from Dell, HP etc and decide on the configuration, but then a similar process is needed to choose from Hetzner vs their competitors.