Hardware & Cost¶
This homelab runs on three refurbished enterprise small-form-factor desktops for the K3s cluster nodes, paired with a Synology NAS for storage — silent, power-efficient hardware purpose-built for 24/7 operation.
Hardware overview¶
| Node | Role |
|---|---|
| node1 | K3s cluster-init (etcd leader) |
| node2 | K3s control-plane |
| node3 | K3s control-plane |
| NAS | Synology NAS (NFS storage) |
Why refurbished enterprise desktops?¶
- Ultra-small form factor — fits on a shelf, no rack needed
- Low power draw — ~10–25W per unit under normal load
- Near-silent — single small fan, rarely audible
- Enterprise-grade NIC — excellent Linux/NixOS support
- Easy to upgrade — M.2 NVMe slot + 2.5" SATA + SO-DIMM slots
- Widely available refurbished — corporate lease returns, readily found second-hand
Specs per node (K3s cluster)¶
| Component | Spec |
|---|---|
| CPU | Intel Core i5/i7 (6-core, 35W TDP) |
| RAM | 16 GB DDR4 |
| Storage | NVMe SSD (NixOS OS + Longhorn replica) |
| Network | 1 GbE Intel NIC |
| OS | NixOS (latest stable) |
Cost breakdown¶
One-time costs¶
The biggest cost driver is the hardware itself. Refurbished enterprise SFF desktops are broadly available on eBay and certified refurbished dealers.
| Category | What you need |
|---|---|
| 3x refurbished SFF desktops | The K3s cluster nodes |
| RAM upgrades (if base config is 8 GB) | DDR4 SO-DIMM kits |
| NVMe SSDs for the three K3s nodes | OS + Longhorn storage |
| Synology NAS (or any NAS with NFS) | Longhorn backup target + media storage |
| USB stick for Ventoy provisioning | Any 32 GB+ USB stick |
Software is entirely free: NixOS, K3s, ArgoCD, Longhorn, Traefik, cert-manager, Grafana, and all self-hosted apps are open source. Let's Encrypt TLS certificates are free. Cloudflare DNS and proxying are free.
The only ongoing paid service is the domain registration (~€10/year).
Recurring costs¶
| Cost | Amount |
|---|---|
| Electricity (3 nodes + NAS, 24/7, ~€0.30/kWh) | ~€15–20/month |
| Domain renewal | ~€10/year |
| Everything else | €0 |
Total ongoing: roughly €15–20/month, almost entirely electricity.
Power draw estimate: three SFF desktops at light load average ~20W each = 60W total, plus the NAS at ~20–30W idle = ~80–90W combined. At typical electricity rates that works out to €15–20/month.
Homelab vs cloud¶
Running the same workload on managed cloud infrastructure:
| This homelab | Cloud equivalent | |
|---|---|---|
| Setup cost | Hardware purchase (one-time) | €0 |
| Monthly cost | ~€17 (electricity + domain) | €80–200+ |
| Break-even | 6–12 months | — |
| After 3 years | Hardware + ~€600 running costs | €2 900–7 200 |
| Data sovereignty | Full — nothing leaves home | Vendor-controlled |
| Learning depth | Hardware, OS, networking, K8s | Managed services only |
A rough cloud equivalent (3-node Kubernetes + NAS-equivalent storage + domain):
- AWS EKS: 3x
t3.medium+ EBS + Route53 — €100–150/month - Hetzner (cheapest viable): 3x CX21 + volumes — €25–40/month
- GKE Autopilot: €80–130/month depending on usage
The homelab pays for itself within the first year compared to even the cheapest cloud option, while giving you full control and better hardware specs.
Network setup¶
The homelab runs on a dedicated VLAN managed by a UniFi gateway.
| Subnet | Purpose |
|---|---|
| Homelab VLAN | All nodes + services (isolated from home LAN) |
| MetalLB pool | Kubernetes LoadBalancer IP range |
| Traefik VIP | Fixed LoadBalancer assignment for ingress |
VLAN isolation keeps homelab traffic separate from the home LAN. All external traffic enters through Cloudflare Tunnel — zero open ports.
Where to source the hardware¶
| Source | Notes |
|---|---|
| eBay | Wide selection, filter by "refurbished" |
| Certified refurbished dealers | Warranty included |
| Amazon — "Renewed" | 90-day return policy |
| Local IT recyclers | Often cheapest, no warranty |
Search for refurbished enterprise SFF desktops (HP EliteDesk, Dell OptiPlex, Lenovo ThinkCentre). Look for 8th gen Intel or newer for good NixOS support and power efficiency.
Optional additions¶
| Item | Why |
|---|---|
| Small UPS (e.g. APC Back-UPS 600VA) | Protects etcd during power cuts — gives ~10 min to graceful shutdown |
| Smart plug (energy monitoring) | Track per-device power and remotely power-cycle stuck nodes |
| Extra drives for NAS | Expand storage without replacing the machine |