Used PC with original macOS

Hey there,
I'm looking to pick up a used computer—just the tower, I don't need a monitor—that comes with a genuine macOS license. I need this specifically for running my business and issuing official invoices, so it has to come from a legitimate retailer or an established online shop so I can get a proper tax receipt.
What would be a decent best buy for around $333?

Thanks in advance!

I'm not entirely sure which retailers specialize in selling pre-owned PCs running macOS. I imagine various corporations offload their old hardware eventually, though I'm curious about the specific channels they use to liquidate them.

Take this one from $250

What about this option? Looks like a solid deal to me.

http://rabljena-racunala.com/index.p...product_id=379

Nah, that's a worse deal. The machine itself is actually pricier, and it looks like you’ll still have to cough up those extra amounts listed below just to get macOS installed.

EDIT

It seems like you'd be getting Windows 7. Honestly, if I were in your shoes, I'd grab that first option and just upgrade it yourself with a 128GB SSD. Just make sure to double-check their policy on the warranty—see if they'll slap a seal on it or something. Or, you could always just bring your own drive to them.

Are you seriously talking about that suggestion you made up above, $250? Honestly, I’m just not in the mood to mess around with swapping out SSDs right now—I need something ready to go and productive immediately 🙂
Do you think it's possible to find a decent, brand-new setup for around $667 that comes with macOS pre-installed?

Nothing worth it there. It’s just some basic minimum configuration for $500, and you're looking at a win of about $267
.
Look, that setup is ready to go right out of the box. My only advice? If 80GB feels too tight, just grab that other build you found. Honestly, the price gap isn't even worth the headache—you can snag a 250GB hard drive for $33, maybe even less. But if you aren't interested in playing DIY scientist with your hardware, you don't really have another choice.

What would be a decent, low-budget entry point for a new build running macOS?

Intel Core i3-6100 with ASUS Prime H110M-E
MSI H110M PRO-D
4GB DDR4
1TB
400W Naviatec (or just whatever cheapest power supply you can find)
Case
A total space heater

+ macOS sold separately (depending on which version you want)

Thanks a ton—I'll probably end up going with one of these two options 🙂

And you think 80GB would be enough for him?

Yeah, I figured that out too—it’s plenty enough if all you need is an invoice for the books. The real headache is that nobody at that shop actually picks up the phone, so I’m basically being forced into the more expensive route just to get things done.

I stumbled upon this other option as well, but honestly, it looks like a total downgrade:
http://rabljena-racunala.com/index.p...product_id=293

We picked up some used rigs from those guys. They were decent enough, came with a clean install of macOS

Try giving them a call in San Jose; I'm pretty sure that's where their headquarters is located

If I remember right, shipping was free

Finally pulled the trigger on a new PC and honestly? It’s killer. 🙂
Big thanks to everyone for the input and all the solid advice!