Help needed with NAS build

[suedenimes]

I'm currently in the process of putting together a NAS build for myself. Unfortunately, I am faced with both a overabundance of choice and a lack of choice. 

 

My situation is that I have recently moved from the UK to the Republic of Ireland. Prices in Ireland are very high across the board and many UK retailers won't ship to Ireland. (I've no interest in any sort of political discussion on Brexit). Without boring everyone with details, I can get my hands at a reasonable price on some stuff, but not others. Some stuff I just can't find at any price. 

 

I had been considering buying a Synology DS920+. This is a four bay NAS that I can pick up for about €520 without drives. I have a budget then where I would like to hit a similar price point (without drives). This NAS is going to be used at home for my wife and I. We want to use it as local backup as well as for PLEX. Want to be able to stream 4K HDR content locally to a Shield TV Pro as well as transcoding a bit of content remotely as needed. I'll also be running a variety of docker containers for things like Sonarr and Radarr (plus torrent client if needed) and other cool stuff as I come across it. Will also be using OpenVPN

 

I will be buying a couple of 4TB Ironwolf drives initially but want to expand that storage as I go. I need a minimum of 4 bays but more would be good. Power consumption is an important factor to consider with current electricity prices. I don't need to hit some absurdly low level of power draw but I don't want to run up huge bills either. I don't have any spare parts lying around for this.

 

The sort of components I have been looking at are something like this :

 

Core i3-10105

H510M-HVS Motherboard

AEGIS, DDR4-3000, CL16 - 16 GB Dual Kit

Fractal Design Node 804 (Note : Have been unable to find one of these I can get delivered)

Unsure of a PSU - Looking at various 80+ Gold options. Unsure if spending the best part of €200 on a platinum PSU is cost effective

 

I am very open to suggestions on what I should consider changing. I'm open to buying second hand kit as well, if I can get my hands on it. I've looked at things like HP Elitedesk desktops with 8th gen i5s but they all have very few drive bays. As I understand it as well they use non standard motherboards so you couldn't easily transplant them into something with more space. I'm open to correction on that.