> At home: 12 or 42 €/month (details¹), depending on whether I want gigabit upload or not.
Your consumer gigabit connection is not comparable to a DC gigabit connection. Your ISP is over subscribing 20x and hoping people don’t use anywhere near their capacity. To make it fair you should compare it to a business plan with a proper SLA.
If I am that serious, then I'd also want the redundant power and would have a budget for it. For business, 130€/month is going to be a fraction of the cost of your first employee. The scenario posed was "as a normal consumer".
Your consumer gigabit connection is not comparable to a DC gigabit connection. Your ISP is over subscribing 20x and hoping people don’t use anywhere near their capacity. To make it fair you should compare it to a business plan with a proper SLA.