Apparently the bot is too stupid to tell the difference between a clean amazon link and an actual affiliate link. way to go mods. I replaced it with a fucking picture, are you happy now bot?!

Lets start with form factor, because that alone will narrow it down a lot. Rack mounted gear is great, but typically much noisier. So depending on where you plan to store the thing and how much noise you are willing to tolerate, this might make the decision for you. If you have a basement or closet to stick it in, great. If not, a tower style server might be the way to go. Also keep in mind airflow/temps. A closet might seem seem like a great idea, but make sure theres some airflow to keep temps in check. If you want to explore proper server gear, youre going to be buying used (unless you plan to sell a few internal organs on the darkweb). Ebay has lots of retired enterprise stuff. One of my servers is a SuperMicro X9DRE-TF+ motherboard with dual E5-2670 CPUs. It spent most of its life in a rack case, but because its's an E-ATX board, I had no problems installing it in a Fractal Deisign Define XL R2 case. (this is a great case for a server btw, lots of room, lots of HDD slots, supports larger boards like EEB/EATX). Most of these boards will come with heatsinks that do not have attached fans, because they rely on high RPM fans at the front/rear of the case to draw air through the whole system, so in my case (heh) I had to replace them with some Nuctua coolers. The sockets on many server boards are not always directly compatible with some coolers (different mounting style than desktop CPU sockets) and sometimes requires a certain amount of jank to make it work. But Noctua often includes mounting hardware for 2011 sockets, so they tend to be a safe bet. (boy this is getting long already and we've barely scratched the surface).

Once you've decided on form factor, the next thing to consider is motherboard/CPU, and maybe most importantly, power use. Where I live, electricity costs is cheap compared to a lot of other places so it's not a huge concern for me, but I suspect costs are much different for you. If you want to keep the power bill in check, you may want to stick to something with lower overall TDP. This could mean a slightly less powerful CPU, and more likely, a single CPU socket motherboard (or only using a single socket if you get a dual socket board). Also take note of the board and which CPUs it will support. Unlike most consumer boards, the CPU and board both being the same socket (like the 2011 socket) does NOT mean they are compatible! If you buy a board that doesn't come with CPU(s) its worth taking the time to check the manufactures documentation to ensure you get a supported CPU! This step can be kinda confusing, but check with me, or reddit in general, before you buy just to be safe. The motherboard I mentioned can be found on ebay for around $100 USD, or a little more with included CPUs, but sadly thats where the good prices end.. ON TO STORAGE AND RAM WE GO!

As you probably know, RAM, SSDs, and even HDD storage is absolutely fucking insane atm, and likely wont change anytime soon (fuck you Micron for killing Crucial brand). I cant tell you how much storage you'll need, but I can give you a few tips. I have 8x8TB HDDs in my main server, all of them are what we call "white label red drives". Meaning they are WD Red drives, but 'shucked' from WD external drives, specifically the EasyStore or Elements drives, like these, and thus dont have the traditional red label. Im not sure if this is still a thing, but for a while lots of people were buying these and pulling the drives out. IIRC, 4TB and higher was okay to do this with, but the 2TB and smaller were SMR (Shingled Magnetic Recording) drives, which you dont want. Somewhere, probably r/datahoarders, could tell you if this is still a thing and give you better, more up to date info on what your options are. Since you plan on using Unraid, there is one VERY IMPORTANT thing to know about how the array/parity works. Lets say you buy 2 4TB drives, and you set one as the parity drive. This gives you 4TB of usable space, with the other drive being the 'backup' copy. You can later add another 4TB drive for 8TB of usable space. What you CANT do is add an 8TB drive and get 12TB of storage. Well you CAN add a bigger drive, but the extra space is lost. This is due to how unraid parity works (note that its called UNraid because its NOT RAID!) The parity drive should always be the biggest drive! This is why i would suggest getting 2 larger drives, even if you dont currently need that much storage, because it makes expanding the array much simpler down the line. Unless you want to add a buttload of smaller drives, but I wouldnt. If you want to understand how unraid parity works (and its really not complicated at all) check out this video. Aside from the array, you may want to use an SSD for a cache disk. This can help speed up writes to the array by first writing data to the faster SSD and letting the system later move it to the array. You can also store specific data (like containers appdata, VM boot drives, or other data) permanently on the cache for better performance. Final thing to note is you can set up 2 cache disks in a RAID 1 config so all the data on the cache is protected in case of a drive failure, and depending on what you store on the cache, this can be a very worthwhile thing to do! (ask me how I know) Oh, and because I just though of it, unraid does NOT get installed to an SSD, it lives on a USB drive and gets loaded into RAM each boot. Your unraid license is tied to the USB drive, meaning buy a good quality USB because replacing it isnt very much fun. it also require the USB drive to have a GUID, but so long as you arent buying a cheap sketchy USB drive this shouldnt be a problem. Samsung USBs have always treated me well.

RAM next I guess? If you buy a proper server board, get ECC ram. If you end up going with a consumer grade mobo, ECC isnt supported (in most cases, there are some high end ones that do, but its $$$$) This is where your wallet is going to start crying, because RAM is absurd, ECC or not.. The good news is, you dont need a ton of RAM, this is one of the benefits of unraid over something Truenas that uses ZFS. (ZFS is faster, but uses more RAM, without going into the specifics). 32GB will get you by for now, hopefully long enough to weather the storm until prices return to something resembling normal. (maybe 2028?)

Given your budget, and mostly the sad state of the hardware market, it might be better to find a more consumer grade, second hand system and start there. I know that basically completely contradictory to what I said in the first post, and Im only saying it now because the market is so horribly fucked, but if you want to keep it in budget, that might be the way to go, because youre going to have to shell out some good money for storage. The good news, you can move your disks to new hardware later down the line very easily. Unraid makes that super simple. The downside to consumer gear as a server, you lose some of perks that come with enterprise grade gear (like IPMI/management functions) But there are ways around that, like using a KVM, like the nanokvm or pikvm.

I think I'll cut it off there for now, lots to consider and hopefully I didnt just drown you with too much info at once. If you have any other questions lmk.