Why pricing is the highest-value competitive signal
A pricing change affects every open deal immediately. It changes what a seller should say tomorrow, it changes discount policy, and it is the competitor move a customer is most likely to bring up first.
It is also the one most teams find out about last, because nobody checks a competitor pricing page on a schedule, and the page itself does not announce that it changed.
What a list price actually is
A list price is a negotiating position, not a transaction. What a competitor prints on that page tells you their packaging, their segmentation, what they have decided to charge for, and what they have moved behind a sales conversation. It does not tell you what anyone paid.
The structure is often more informative than the number. A feature moving from a lower tier to a higher one, a usage limit tightening, a plan disappearing, or a price being replaced by contact us all describe a strategy, and all are visible on the page.
The evidence problem, and the fix
A change claim needs a before and an after, each with a date. There are two sources for the before: a public web archive, which gives you history you never collected, and your own captures, which you control and which are usually more frequent.
The practical approach uses both. Archived captures give a history on day one. Your own captures, taken on a schedule and fingerprinted so that a rotating banner does not register as a price change, give you dated evidence going forward that you can produce when someone disputes it.
Watch enterprise pricing too, especially when it disappears
A company that removes its prices in favour of contact sales has usually moved upmarket, and that is a competitive fact worth knowing even though no number is visible. The absence is the signal.