Monitoring at a flat monthly price.
Per-call pricing is the cheapest path when you are building something, but if the job is simply watching for a keyword, a flat monthly plan is often the cheaper and simpler fit. Managed monitoring runs from $19 to $199 a month by monitor count, with webhook, Slack, and Discord delivery, and 11 monitoring endpoints behind it. The price does not move with how much it matches, so a busy month and a quiet month cost the same and nobody has to write a polling loop.
Both buyers are real, so this site sells both. If you want to own the pipeline, pay per call; if you want alerts without running one, the flat plans are on the pricing page next to the per-call rates, and the product is described on the Reddit monitoring API page.
The way to pick between the two is to be honest about who acts on the data. If a program consumes it, pay per call and keep the pipeline; the flat read rate stays the cheapest unit once you are making thousands of calls. If a person reads an alert and decides what to do, the managed plan is usually cheaper than the engineering time a home-built watcher costs to write and keep running, even though its sticker price is higher than a handful of reads. The cheapest option on this page is therefore not a single line item; it is whichever model matches how the data gets used, and both are priced so you can start on either for a few dollars and switch without a contract if the first guess was wrong.
One more cost hides in the gap between the two models. A home-built watcher on the per-call API is cheap to run but needs someone to own the polling loop, the dedupe logic, and the delivery retries, and that maintenance is the same work the managed plan already does. So the real comparison at the mentions-watching job is not $0.0015 a read against $19 a month; it is the read cost plus the hours to build and babysit the watcher against the flat plan that ships those parts already solved. For a team whose time is worth more than the difference, the flat plan is the cheaper of the two even though the per-call rate looks lower on paper.