Cheapest 16x4tb NAS

New update: my current setup is a dell power edge t310 with 6x4tb SAS, zeon CPU, and 12gb ECC all parts stock. No hardware raid. 2.5gb network card. Should I just replace the 6 drives? With larger capacities? That will probably be more than $10/tb... I didn't buy the 16 drives yet, they are used SAS drives 4tb each, turn to be about $40 each.

Current storage 8tb used out of 14... And lots of cold drives waiting to get copied... 10tb+ probably. Is it worth copying all the cold storage drives to the redundant nas.

Update: budget(200-600), the reason for the build is I found cheap 4tb drives for almost $10/Terabyte. So I want to use as much of them as I can

I am trying to build my final NAS build as a beginner.

I have a 6x4tb dell server, but it's not enough.

I am currently trying to build the final boss of my nasses. 4x16tb with truenas with raid

I am unsure of what parts to buy as I am a complete beginner.

I found a case that can hold all 14 drives.

I need a motherboard, CPU, ram, PSU

I am on a budget, kind of.

What motherboard do you recommend? Pulled from a workstations with CPU and ram? A server board? Normal consumer with normal consumer CPU? Motherboard should have some pcie slots for 2 sata cards and one 2.5 GB card.

What CPU to run all these drives?

What ram and how much? 16? 32? Ecc, non ecc? Ddr4? Ddr3?

Power supply: 850w or more?

All parts should be able to support the 16 drives with headroom...

I would appreciate any help on this build, I want to build this as soon as possible.

Thanks