Easy to figure out:

• Ryzen 5800X3D: $300
• ROG Strix X570i: $150
• iCue h110i Elite LCD: $200
• Corsair Vengeance: $70
• Samsung 980 pro 2tb: $120
• EVGA Supernova 850 Gold: $120
• Meshilicious case: $150 (little extra for the mods)
• 4 Noctua fans: $125

That means everything without the GPU is $1235. I have no idea what a 4080 costs these days, so if you think $515 is a good price for it, then I'd say it's a good deal.

ETA: Even though AM4 is EoL, a 5800X3D will serve anyone well for probably 6-10 years.

I think so. The 4080 alone is like 1300 bucks. I would try to haggle to 1500, since the system is used.

Pretty decent deal for the parts given, though I would also consider if you agree with those parts.

For instance, there might be a killer deal on a 4090, but I wouldn't buy it anyways because I don't want a 4090/I still wouldn't want to pay the discounted price. You should think about whether those parts are parts that you want.

AM4 is somewhat old, but most of the selling price in this case is from the absolutely insane market price of a 4080. Frankly, if I were aiming for that performance tier, I would have gone for a 7900XTX, but Nvidia does have better productivity and ray tracing. Regardless, the 5800X3D holds up very well, even against modern generation halo products. So as long as you're not planning to upgrade the CPU anytime soon, I expect that going AM4 shouldn't be a problem