How the Price Trackers Work: Sources, Filters and Math
Every number on the trackers comes from rules you can read. These are the rules.
By Brandon Sheley · Updated
In short: the trackers pull current listings from the PricePerGig API (drives) and eBay's official API (everything else) every few hours, drop accessories, parts and wrong-model matches, log what's left to a history database, and report medians with outliers removed. Solar is a hand-checked catalog.
If you're citing a number from one of the trackers, this page is what it means.
Where the Listings Come From
| Tracker | Source | Refresh |
|---|---|---|
| Hard drives & SSDs | The PricePerGig API, which covers several marketplaces (pricing data courtesy of PricePerGig.com) | Every few hours (6-hour cache) |
| Mini PCs | eBay's official Browse API, one search per product line (OptiPlex Micro, EliteDesk Mini, ThinkCentre Tiny, NUC, Beelink, Minisforum, Intel N100 and N305 boxes) | Every few hours (6-hour cache) |
| RAM | eBay Browse API, by form factor and DDR generation | Every few hours |
| GPUs | eBay Browse API, one search per card | Every few hours |
| NAS | eBay Browse API, one search per model | Every few hours |
| Servers | eBay Browse API inside eBay's Computer Servers category | Every few hours |
| Switches | eBay Browse API, one search per model | Every few hours |
| Solar | A hand-checked catalog of retailer prices; solar retailers don't offer a listings feed | When I re-check it |
Each eBay search pulls the cheapest current fixed-price (Buy It Now) listings. Prices are asking prices from live listings, not completed sales; each listing's detail page adds shipping to show the landed price when the listing provides it.
What Gets Filtered Out
- Accessories and parts. Each tracker has a blocklist of title words for things that mention a product without being one: GPU brackets and coolers, server motherboards, backplanes and rail kits, mini PC stands and caddies. On the server tracker, words like "memory" or "PSU" only block a listing when the title shows no CPU or configuration.
- Price floors drop listings too cheap to be a working unit (for example $60 for GPUs and mini PCs, $150 for servers, $20 for switches).
- Wrong-model matches. eBay's search returns near matches, so GPU and N-series mini PC listings have to name the searched model in the title, and GPU listings that name several cards at once (multi-card "variation" listings) are dropped.
- Old hardware on the mini PC tracker: pre-6th-gen Intel machines are dropped.
- Duplicates: identical title-and-price listings collapse into one row.
- Flagged, not hidden: for-parts, as-is, untested and barebones listings stay on the tracker with a badge, but are left out of every statistic.
How Price History Is Logged
Every refresh writes the listings it found to a price history database. For statistics, each listing counts once per day, at its lowest price that day, so a listing that sits for weeks doesn't outweigh one that sold in a day. Hard drive and SSD history starts September 2, 2026; the eBay trackers started logging October 11, 2026.
When filter rules change, already-logged rows that the new rules would reject are purged once, so old junk doesn't linger in the history.
How the Numbers Are Calculated
- Typical price is the median, not the average, so a handful of overpriced listings can't pull it up. On model and drive-size pages it covers the last 90 days.
- Outliers under 30% or over 3x the median are dropped before calculating anything.
- Per-unit value is price divided by the unit that matters: $/TB for drives, $/GB for RAM, $/GB of VRAM for GPUs, $/bay for NAS and servers, $/port for switches, $/W for solar. Mini PCs have no single natural unit, so they rank by price.
- Lowest we've seen is the lowest working listing-day price after those filters, with its date.
- Monthly figures on the Homelab Hardware Price Index are medians of every listing-day in the month.
Which Pages Search Engines See
- Tracker pages, model and drive-size history pages, and the price index are indexable. Model pages stay noindex and out of the sitemap until they have at least 14 days and 30 price points of history, then join automatically.
- Individual listing pages are noindex. They're short-lived and mostly the seller's content, and they redirect to the filtered tracker once a listing ends.
Links and Independence
Links go to the listing as the source returned it. I don't add affiliate tags to them, and the trackers don't take payment for placement. They're personal tools I built for my own buying and share because they're useful; always check the listing itself before you buy, since prices and stock change between refreshes. If you spot a listing that's clearly in the wrong category, tell me and I'll tighten the filter.
Related Resources
All Price Trackers
Every tracker this methodology covers.
Homelab Hardware Price Index
Monthly medians computed with these rules.
Hard Drive & SSD Prices
The longest-running history, back to September 2026.
Mini PC Price Tracker
Live eBay listings with the filters above applied.
GPU Price Tracker
Where the model-match and multi-card rules apply.
About Brandon Sheley
Who builds and maintains these trackers.
Frequently Asked Questions
Are the tracker prices sold prices or asking prices?
Asking prices. Every figure comes from live fixed-price listings, not completed sales. Asking prices track the market closely but usually run a little above what things actually sell for.
How often do the price trackers update?
Every few hours. Hard drives and SSDs come from the PricePerGig API and the other hardware trackers from eBay's official listings API, each cached for up to six hours. The solar tracker is a hand-checked catalog updated when I re-check retailer prices.
How is the typical price calculated?
It's the median of logged listing-days, with each listing counted once per day at its lowest price that day. For-parts and as-is listings are excluded, and outliers under 30% or over 3x the median are dropped first.
Do the trackers use affiliate links?
No. Links go to the listing as the source returned it, without affiliate tags added by me, and no one pays for placement.