My mini PC cluster bill of materials went stale in ten days. The cluster design did not change. The marketplace evidence underneath it did.
That is the bug. I published a durable architecture and an expiring shopping cart as if they had the same shelf life.
This is the maintained version: a hardware specification, price ceilings, saved searches, and a dated market snapshot. A listing can disappear without invalidating the recommendation.
What Went Stale
On August 12, I published the cleanest three-node cluster I would buy. It named a safe listing and a cheaper no-return listing.
The $119 listing is no longer verifiable. The safer Ingram Micro listing remains at $169.99, but now shows an 8% checkout coupon. Its effective price is $156.39 before Seattle tax.
| 1 | August 12 snapshot: |
| 2 | safe node: $169.99 |
| 3 | cheapest node: $119.00, no returns |
| 4 | conservative stack: $716.30 delivered |
| 5 | |
| 6 | August 22 snapshot: |
| 7 | safe node: $169.99 listed |
| 8 | checkout price: $156.39 with 8OFFAUGUST |
| 9 | cheapest listing: no longer verifiable |
| 10 | architecture: unchanged |
Nothing important happened to the i5-8500T, k3s, the workload, or Seattle power prices. Inventory moved. A coupon appeared. One sentence claiming “the cheapest” became false.
A used-hardware article should not promise that one listing will survive. It should explain why a class of machines works and define the price at which the answer changes.
Separate the Architecture From the Cart
The architecture still wants three matching six-core business minis. The cluster still needs 24 GB of aggregate memory, local SSDs, a UPS, and boring gigabit Ethernet.
HP, Dell, and Lenovo all sold machines in this class by the pallet. The brand matters less than matching nodes, included adapters, return protection, and enough inventory to buy all three together.
| 1 | Required: |
| 2 | quantity: 3 matching units from one seller |
| 3 | CPU: i5-8500T, i5-9500T, or equivalent 6-core x86 |
| 4 | memory: at least 8 GB per node |
| 5 | storage: at least 256 GB SSD per node |
| 6 | network: wired gigabit Ethernet |
| 7 | accessories: power adapter included for every node |
| 8 | protection: 30-day returns and at least a one-year warranty |
| 9 | |
| 10 | Good families: |
| 11 | HP: ProDesk 600 G4/G5 Mini, EliteDesk 800 G4/G5 Mini |
| 12 | Dell: OptiPlex 7060/7070 Micro |
| 13 | Lenovo: ThinkCentre M920q/M920x Tiny |
| 14 | |
| 15 | Not required: |
| 16 | Windows license, Wi-Fi, keyboard, mouse, matching cosmetic grade |
Eight gigabytes and 256 GB are starting points, not lifetime limits. These machines can be upgraded after memory pressure or storage use makes the upgrade concrete.
Paying for 32 GB and 1 TB in every node is wasteful when the workload does not need it. Paying for returns is useful on the day one of three used machines fails its burn-in test.
Search for a Class, Not a Listing
Product links are evidence for a dated snapshot. Saved searches are the durable entry point. I would check these three before purchasing:
Search results are candidates, not facts. Open the listing and verify the actual CPU, installed memory, SSD, quantity, adapters, shipping, returns, and warranty.
I still prefer eBay Refurbished when the premium is modest. The program advertises free shipping, 30-day returns, and a one- or two-year warranty.
Use Price Ceilings
A ceiling turns an endless search into a decision. At or below $170 per node, I would choose the cleanest protected listing and stop shopping.
Below $130, I would inspect the tradeoffs. Above $200 for an 8 GB, 256 GB eighth-generation node, I would wait, negotiate, or move to another model family.
| 1 | Safe lane: |
| 2 | node ceiling: $170.00 |
| 3 | three-node ceiling: $510.00 |
| 4 | UPS budget: $120.00 |
| 5 | switch + cables: $35.00 |
| 6 | pre-tax ceiling: $665.00 |
| 7 | Seattle tax: 10.55% |
| 8 | delivered ceiling: $735.16 |
| 9 | |
| 10 | Deal lane: |
| 11 | node ceiling: $130.00 |
| 12 | tradeoff: used condition or weaker returns |
| 13 | rule: buy only if all three adapters are included |
| 14 | |
| 15 | Walk-away line: |
| 16 | more than $200 for an 8 GB / 256 GB eighth-gen node |
The $155 support budget is intentionally a cap: $120 for a UPS and $35 for a five-port gigabit switch plus cables. A ventilated shelf is still cheaper than pretending this is a rack.
The delivered ceiling uses Washington's official Q3 2026 10.55% Seattle sales-tax rate. Shipping must fit inside the ceiling too.
August 22 Snapshot
The Ingram Micro HP ProDesk 600 G4 listing still has more than ten units. It lists at $169.99 and shows $156.39 after coupon code 8OFFAUGUST.
The listing includes free shipping, 30-day returns, and a one-year warranty. If the coupon applies to all three units, it clears the safe lane by almost $45 before tax.
| 1 | Current safe listing, verified August 22, 2026: |
| 2 | checkout node price: $156.39 |
| 3 | three nodes: $469.17 |
| 4 | support budget: $155.00 |
| 5 | pre-tax total: $624.17 |
| 6 | Seattle tax: $65.85 |
| 7 | delivered ceiling: $690.02 |
| 8 | |
| 9 | Recurring estimate: |
| 10 | power: $9.13/month |
| 11 | B2 backup: $1.81/month |
| 12 | total: $10.94/month |
| 13 | |
| 14 | Effective cost: |
| 15 | 24 months: $39.69/month |
| 16 | 36 months: $30.11/month |
The recurring estimate still uses 85 W for the stack, 10% UPS overhead, and Seattle City Light's $0.1338/kWh flat residential rate.
The backup line still models 260 GB at Backblaze B2's $6.95/TB-month pay-as-you-go price. Those inputs are versioned separately from the hardware listing.
| 1 | support_budget = ups_budget + network_budget |
| 2 | delivered = (node_price * 3 + support_budget) * (1 + sales_tax) |
| 3 | effective_monthly = delivered / months + power + backup |
| 4 | |
| 5 | # August 22 inputs |
| 6 | node_price = 156.39 |
| 7 | support_budget = 155.00 |
| 8 | sales_tax = 0.1055 |
| 9 | power = 9.13 |
| 10 | backup = 1.81 |
Without the coupon, the same configuration is still inside the $735.16 delivered ceiling. The coupon changes the checkout total, not the architecture decision.
The Refresh Loop
I do not need to rewrite the cluster guide every time a seller edits a coupon. I need a small procurement record and a rule for when new evidence changes the conclusion.
| 1 | Before buying, or every 30-60 days: |
| 2 | 1. Open all three model-family searches. |
| 3 | 2. Require three matching units and three power adapters. |
| 4 | 3. Record listing ID, quantity, price, coupon, returns, and warranty. |
| 5 | 4. Recompute the delivered price from the formula. |
| 6 | 5. Stop when a safe listing is below the ceiling. |
| 7 | 6. Update the article only when the recommendation or ceiling changes. |
The snapshot should record observed facts, not predict availability. The durable post should keep stable requirements and formulas. Each can then age at its natural speed.
If a safe listing stays below the ceiling, update only the verification date. If every model family crosses the ceiling, revisit the hardware class. If power changes materially, update the operating-cost model.
Decision
I would still buy three matching HP ProDesk 600 G4 Minis from the current protected listing. I would use the coupon if it applies to all three and walk away if checkout exceeds the ceiling.
The old article remains useful as an August 12 market snapshot. This post becomes the buying guide: specification first, search second, listing last, and every volatile number visibly dated.