Direct answer: Scan for older hardcovers with intact dust jackets, check the copyright page for a first-edition number line, and use a phone to quickly cross-reference the ISBN or title against AbeBooks sold listings before deciding whether a find is worth buying.
Why thrift stores are a real sourcing channel
The U.S. secondhand book market has grown steadily for years, and thrift and donation-based stores are a meaningful part of that supply chain, since the books moving through them are typically priced by volume rather than individual title research.
What experienced hunters actually look for
Dust-jacketed hardcovers in strong condition, especially first editions of established authors, illustrated or design-forward editions, and out-of-print nonfiction in narrow subject areas tend to hold the most resale or personal-collection value relative to their thrift-store price.
Checking value on the spot
A quick phone search of the exact title, author, and edition on AbeBooks' sold-listing history (not just current asking prices, which can be inflated) gives a realistic sense of what a specific copy is actually worth before you commit to buying it.
Timing and store rotation
Most thrift and used-book donation stores restock shelves on a predictable schedule; asking staff when new donations typically go out gives a real edge over showing up at random.
Are thrift store books usually first editions?
Rarely, but it happens often enough that checking the number line takes only a few seconds and is worth the habit.
What's a reasonable price to pay before checking value?
Most thrift stores price books low enough (often a few dollars) that even a wrong guess is low-risk, but checking first avoids missing an obviously underpriced rare find.
Do library book sales work the same way?
Yes, library used-book sales are one of the strongest hunting grounds since donated collections often include older, well-cared-for personal libraries.