Where I live, electricity is also very expensive. I monitor every watt.
I asked the same question half a year ago, here's what I've learnt: RPis tend to be less reliable and aren't that energy efficient. They're great for small appliances, but for servers (e.g. NAS) not as much.
Get an used Thinclient/ mini PC. They cost something between 50-150€ and give you a huge performance boost, more ports, a x86 architecture, are better repairable (still often bad) and more.
Mine uses about 10-15 W on normal use, and 20 rarely when my cloud is under heavy use.