$3500 budget for local LLM + eventual Proxmox homelab node. What would you buy?

Hi all. Trying to figure out the right hardware and want outside input on the whole decision instead of anchoring on a build I already have in my head.

Budget: $3500 hard cap, spent during a trip to Barcelona in September 2026. I'm based in South America, so this travel window is genuinely valuable to me for buying hardware that's hard or expensive to get locally.

On buying used: I'd rather buy new given the risk, but if used gets me a real jump in quality for the same money, I'm open to it. I don't know how to properly check a used card's condition though, so any advice on how to test one on the spot and actually be confident it's in good shape would help a lot.

What I already have (stays regardless of what I buy):

• Raspberry Pi 5 (8GB), always-on edge node: DNS, monitoring, backups. Not a compute candidate.
• Desktop: i5-13600K, 78GB DDR5, RTX 3060 Ti 8GB VRAM. This is my daily driver for work, and it currently also doubles as my only LLM node, woken on demand (WoL) when needed. I'd like to eventually separate "the computer I work on" from "the box that runs LLMs," but that's not urgent yet.

Primary goal: local LLM node for:

1. Live coding assistance alongside Claude (Sonnet/Opus/Fable): offloading agentic steps that don't need frontier-model judgment, to cut paid API token spend.
2. Long batch jobs where latency doesn't matter, hours to overnight: image analysis, code review passes, hybrid web scraping.
3. An uncensored model for security-testing / pentest-adjacent work.
4. Behind all of it: privacy (data stays on my network), avoiding vendor lock-in, and lower ongoing spend on paid tokens.

I'm not trying to replace Claude for complex agentic work. This runs in parallel as the cheap/private/good-enough lane. With the hardware you'd recommend for this budget, would I be able to run something like Qwen3.8 or another decent MoE model at a usable speed, and is it actually worth running versus a smaller/older dense model?

Secondary goal, can wait: a Proxmox homelab node, either combined with the LLM hardware or separate, depending on what makes sense. Planned to eventually host: OPNsense (firewall/VLANs/DHCP), a Docker-Compose VM (Jellyfin, Immich, n8n, CouchDB, Vaultwarden), a Windows VM with GPU passthrough for creative work and gaming, plus small LXCs for DNS and home automation. Not urgent, could be phase 2 with a separate budget.

Hardware traits that matter regardless of what I buy:

• Room to grow later (more RAM, more GPU, more storage) rather than a sealed/maxed-out box. If a given path turns out to have no real room to grow, that's not a dealbreaker either: I'd just resell it down the line and put the money toward something better.
• Quiet under load, since it'll likely sit somewhere I spend time in. This isn't a hard constraint though: if the best option for my use case is loud, it can just live in another part of the house, so don't let noise rule out a recommendation on its own.

What I'm asking:

• Given this budget, these use cases, and what I already have, what would you buy? GPU-focused build, unified-memory mini-PC/NAS-type box, or something else entirely. All open.
• Does it change your answer once the Proxmox/homelab use case is in the mix, even as a "later" goal?
• For my LLM use mix (interactive coding-assist + unattended batch + uncensored model), what spec matters most: VRAM headroom, memory bandwidth, raw compute?
• How do you expect the used/new hardware market to look over the next year or two? Trying to figure out if it's smarter to buy now on this trip or wait for prices/availability to improve.

Appreciate any pointers, happy to give more detail if useful.

(Not a native English speaker, used AI to help clean up the writing here, sorry for any leftover awkward phrasing.)