An HP P4515x.
Tough to find accurate information on the actual price and release date, BUT this is what ChatGPT said (take with a grain of salt):
> me: when was the HP P4515x released? Roughly how much did it cost?
> ChatGPT: The HP LaserJet P4515x printer was released in 2008. It was designed for businesses with high-volume printing needs. At launch, the price of the HP LaserJet P4515x was around $1,800 to $2,000, although prices could vary based on the retailer and any additional features or accessories purchased with the printer. Keep in mind that the cost for such a printer model would likely decrease over time due to the introduction of new models and advancements in technology.
So I was mistaken, it wasn't $4000 new, it was closer to $2000, and it's closer to 15-16 years old. That's what I get for writing stuff without double checking.
I didn't pay anywhere near that, I bought it in 2020 used for like $150. The UberXL I had to take to get it back to my house was like another $80.
ETA: I should point out that if you decide to buy one, make sure you buy a RAM upgrade as well. It comes with too small of memory for modern documents; when it prints even moderately sized PDFs you just get an out of memory error. I bought the 512MB RAM expansion for very little (I'm having trouble finding the listing that I bought from, but I think it was on the order of $25 on eBay with shipping). Once I did the upgrade, it's been a perfectly decent printer; it doesn't do color but I almost never need color; all I ever print are documents, generally created with LaTeX, and it works fine.
Also, if you decide to buy this specific model, email me about the firmware upgrade process. HP's documentation on doing it is actually wrong and I had to figure it out myself, and the trial and error process cost me an entire ream of paper!