Peter laments over his totaled apartment following Spider-Man's battle with Green Goblin. Although invited to stay with Flash Thompson, Peter reconsiders when he finds out Flash lives in faraway Queens! Plus, the introduction of Mindworm, a strange mutant with the ability to manipulate emotion.
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Amazing Spider-Man #138 is a perfect example of why comic buying decisions feel harder than they should.
Some grades quietly compound while others stall. Price can look reasonable and still be misleading. And what feels “stable” on a price guide often hides risk that only shows up later.
I struggled with this for years — even on iconic books like this one.
The issue wasn’t access to more data. It was misreading the signals that actually matter when deciding if — and how — to buy.
I documented the framework I now use to make these calls — the same thinking behind Underval’s fair-value logic.
How to stop misreading the comic market before it costs you.
The last recorded sale was a CGC 9.4 for $115 on 03/23/2026 at eBay.
The highest recorded sale was a CGC 9.8 for $900 on 09/12/2021 at Heritage Auctions [1].
The lowest recorded sale was a CGC 7.5 for $9 on 06/13/2011 at Comic Connect.
A CGC 8.5 shows the highest inflation-adjusted CAGR at 7.0% over 2012–2026 (14 years).
Average days to sell vary by grade (~every 94–1783 days by grade), ranging from CGC 9.6 every 94 days to CGC 4.5 every 1783 days.
Search by title and issue to explore market data, sales history, and real-time pricing trends for each grade.
Gain insight into key metrics such as Fair Value, Compound Annual Growth Rate (CAGR), and time-based average sale prices by issue and grade.
Quickly find comics like Amazing Spider-Man #138 priced below fair value across the web through auction sites like eBay, based on recent market data.
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Underval is a free comic-book analytics and listings platform. We estimate fair value by grade, display annual growth rate, show recent sales and sales history, and surface active listings.
We aggregate public online sales from major marketplaces and auctions such as eBay and Heritage Auctions, then normalize and de-duplicate them by issue and grade.
Fair value blends recent realized sales with longer-term trends, outlier filtering, and grade-level liquidity. It’s an informational estimate, not an offer.
Values update as new sales appear. Each grade’s “Updated on” date reflects the most recent sale we’ve matched for that grade.
We track Universal CGC-graded copies across common scale points (e.g., 0.5–10). Availability varies by issue and observed market activity.
No. Underval provides data and estimates for research purposes only. Always do your own diligence before buying or selling.
