You would have to get quotes from a few colos and do the math. What you would not be paying in electricity in your apartment you may be paying in colo fees for

You would have to get quotes from a few colos and do the math. What you would not be paying in electricity in your apartment you may be paying in colo fees for bandwidth, rack space, their power, etc... Get detailed quotes and not just an estimate. They will need the number of U's your servers take up, the power requirements redundant, voltage, amperage, etc..., the number of IP addresses, bandwidth requirements and so on. Remember you can negotiate. It won't be much if you only have a few servers but always try. Be careful to read their contract closely as some will have time limited offers and costs can go up if you did not pay attention to the fine print. Your desired SLA will also impact the cost. Read all the reviews on each colo. Some of the really low end colo providers can be jerks and remember they have your servers. If things go sour and you don't have a great contract you may be delayed in getting your hardware back if they think you are a hobbyist or a tiny company that does not have good lawyers.