What NAS OS are you planning on running and what else will it be doing?
Are you willing to write off up to £300+ because you can’t justify 30 minutes building a PC? If so then go for it.
If not, then consider your options:
1: Used.
Truth be told, not that much has changed in CPU terms between the v1 and v5 Xeon’s, minor IPC and power savings is about as exciting as it gets, as a NAS is generally going to be idle a lot of the time, then TDP is largely irrelevant. An older T20 or similar will give you pretty much the same user experience, but leave you with a decent chunk of your budget to spend on storage.
Example: I grabbed a Supermicro SC833 with 8 bay hot-swap backplane, X10 board, 4GB ECC and a G3220 and Server 2012 COA for £118, it’s an ideal basic NAS, you could drop a V3 Xeon in and still be under £160 all in.
My R210-II and 1270v1/8GB was about the same with hardware RAID and 2x1TB. It’s been tweaked since then (now SSD) and last I looked was pulling about 45w with minimal load.
2: New.
The Ryzen 2700 has been discounted to below £160 inc cooler, that’s 8c/16t, 8GB of DDR4 will set you back £40 and a suitable case/board from £100, that leaves you £140 to justify spending 30 minutes assembling it, what else could you (legally) be doing that pays £140 for 30 minutes work? Heck you could chuck £140 at a GPU and it would be a very decent gaming PC.
Of course if you aren’t going to notice the hit on buying a new server then nothing at all wrong with the T30, just it’s not really that great and you pay a premium for warranty you are unlikely to use and ‘new’.