What Agents Buy.

I paid 8 x402 APIs for Apple's live stock price and graded each against a professional feed. Seven matched to the penny at $305.93. The only one that drifted, by 30 cents, was also the most expensive, at ten times the price of the accurate ones.

Financial Modeling Prep sells a professional real-time stock feed. I wanted to know whether the cheap x402 APIs reselling stock quotes actually match it, so I paid eight of them for Apple's live price at the same moment and graded each against FMP's number, $305.93. Seven came back at $305.92 or $305.93, matching to the cent. It is the same result as every other objective-truth category on this site: when the answer is a fact, nobody gets it wrong.

• The number is never wrong. Seven of the eight sellers returned Apple at $305.92 to $305.93, zero basis points from FMP's real-time quote, and the median deviation across all eight was zero. That is the same pattern as the Bitcoin-price, weather and wallet-balance studies: an objective fact has one answer, so accuracy is a solved problem and there is nothing to grade a seller down for. finance.toon.haus returned it for a tenth of a cent, exact.
• Paying more bought a worse number, not a better one. The single seller that drifted, stablefinance.dev at 30 basis points ($305.00 against $305.93), was also the most expensive in the group at two cents a call, four to twenty times what the exact sellers charged. The pattern keeps repeating across this market: price does not track accuracy for commodity data, because there is no accuracy to buy.
• So what is worth paying for here? Not the resold quote, the feed underneath it. FMP, the professional real-time source I graded everyone against, is the thing with value, because it does the hard part: licensing, low latency, coverage, and standing behind the number. The x402 sellers mostly pass that same number through for a fraction of a cent, which is convenient but not exclusive. If an agent needs one AAPL quote, any of the cheap accurate sellers will do; if it needs a feed to build on, that is what a paid professional source is for.

reference: AAPL $305.93  (FMP /stable/quote, 2026-08-17)

matched to the cent:
  finance.toon.haus              $305.93    0 bps   $0.0010
  blockrun.ai                    $305.92   -0 bps   $0.0020
  blockrun-web (same operator)   $305.92   -0 bps   $0.0020
  x402.openwebninja.com          $305.93    0 bps   $0.0030
  2s.io                          $305.93    0 bps   $0.0045
  stock-price.klymax402.com      $305.93    0 bps   $0.0050
  api.x402node.dev               $305.93    0 bps   $0.0050

drifted:
  stablefinance.dev              $305.00  -30 bps   $0.0200   (the priciest in the group)

median deviation 0 bps. total $0.043, reconciled on-chain. every raw response archived.