Been wanting to build a NAS for years, never got around to it, but I'm at the point now where I'm ready to do it.  
 
I'm looking ONLY at a Micro ATX based build here - AMD or Intel doesn't matter.   I would prefer a sub $150 CPU 60W or less for ease in quietly cooling.  Would prefer that motherboard have 3 or 4 M.2 slots, as I already have 3 m.2 drives for use - looking for triple redundancy backups.  I will directly connect to network via network cable, so wifi does not matter.
 
Case wise, I like overall look & the 200mm front fan of the Thermaltake Divider 200 TG Air, don't really like the price though.
 
Memory wise, I'll select something from the motherboard compatibility list once I've chosen the motherboard. 
 
I'm guessing a 400W power supply would be more than enough as this will only ever be used as a NAS. 
 
Would prefer to keep this under $600 for case, memory, motherboard, CPU & power supply.
 
 

Might want to look at the links below over for some info / not all are NAS specific  
 
With the proper CPU choice, you can just use the iGPU & skip buying a dedicated GPU 

Best gaming PC builds:budget, mid-range and high-end ... - PC Gamer
 
Best PC builds for gaming 2024: From $500 budgets to $4,000+ 

NAS build links:


 NAS build
Build Your Own NAS in 2024 - DIY vs Synology/QNAP
 

Here's what I'm thinking of going with:
 
Thermaltake Core V21 case
EVGA 400W PSU
AsRock B760M Pro RS motherboard
Core i3-14100 CPU
G.Skill Trident Z5 DDR5-6000 (F5-6000J3636F16GX2-TZ5RW) 32GB kit
 
Less than $460 after tax & shipping!  But I almost forgot about my car insurance, so the build will have to wait till January.

What is it this NAS is going to do??
 
Plex/multimedia rig? Intel iGPU.
Pure data files? AMD xx90 for the highest horsepower.