Thinking about getting a NAS

For the moment all I have is one, quite full, 2tb drive that I think will fail pretty soon. I have been thinking about getting 2x6tb drives and running them in raid but after watching Wendells videos I'm not so sure about that anymore. I am considering getting a small nas instead, one which I could also use as my personal cloud storage.

However I wonder who do I configure a NAS not using raid? And how much does it cost to have an always on NAS in terms of electricity? Are we speaking like 5 watts? 10? 100?

Sounds like a great idea
The power issue would depend on the components you used I'd say your highest estimate is low or spot on.
Each hard drive you use on max load will pull 20W
typically only about 10W and 5W when spun down only keeping the electronics on

The cpu could be very low power an atom would be just fine to keep up with most things especially if you had an intel nic which will handle most decoding of packets.

Well, If I'd add more drives to my current computer, it would use more anyway. I guess "NAS" rated drives also have some kind of green mode which let's them spin down when not used and such? It would be great for me to have some kind of cloud application and plex server running on the nas but I might have to go for something more powerful for the decoding?

Maybe better to buy an Intel nuc and install freenas and use one of these: https://www.inet.se/produkt/8906400/internt-kabinett-4x2-5-sata-harddiskar

However, a nuc only has 1 sata 6Gbit/s port, connecting 4 drives might be a bit difficult. Also I would need a external power source for the harddrive cabinette.