Depending on the machine this might cost you more in electricity than a VPS. 100watts continuous costs something like $7/mo in a fairly low electricity cost region of the US.
That would be assuming the machine is on 24/7 and only be used for Minecraft. A lot of Minecraft management systems allow the Minecraft server to be shut off when no players are on which would limit how many resources are being used on the machine 24/7 too.
Overall I personally prefer a VPS or dedicated server but I don't think comparing it like you are is 100% fair.
Overall I personally prefer a VPS or dedicated server but I don't think comparing it like you are is 100% fair.