One afternoon last week, a single keyword cost me $4.37 in ten hours.

Not a typo. One keyword — #buildinpublic on X — at the X API's pay-per-use pricing of half a cent per tweet returned. The hashtag produces roughly ninety posts an hour, my poller dutifully fetched all of them every hour, and by evening I'd bought 868 tweets I mostly didn't need. Annualized, that one keyword was on pace for about $360 a year. For one keyword. On one platform.

That incident sent me down a rabbit hole I should have gone down earlier: what does it actually cost to know when someone mentions your product, your competitor, or your problem space on the internet? The answer turns out to be "anywhere from $0 to $4,800 a year," and the difference is almost entirely architecture, not features.

The menu, honestly priced

The suites. Brand24 starts around $119/mo billed annually; useful tiers for a team run $200–400/mo. Mention starts around $41/mo. These are real products with real breadth — news, blogs, podcasts, TikTok, sentiment charts, PDF reports. If you're a brand team that reports share-of-voice to a VP, they're correctly priced. If you're a founder who wants to know when someone on Reddit asks for a tool like yours, you're buying a combine harvester to mow a balcony.

The alert services. Syften (~$15–100/mo) and F5Bot (free, genuinely) watch Reddit, Hacker News, and niche communities and email you on keyword hits. Honest tools, honestly priced. Their limit isn't coverage — it's that an alert is the start of your work. Judging and answering 50 alerts is still your evening.

The APIs, raw. This is where it gets interesting, because the platforms have wildly different philosophies:

Reddit is effectively free if you're polite. Every subreddit ships an RSS feed (/r/yoursub/new.rss) that works without an API key — you need a descriptive user-agent and respect for the rate budget (about 100 requests per 7-and-a-half minutes per IP). For watching specific communities, this is the deal of the decade.
Bluesky is free, full stop. The AT Protocol's search endpoint is open, unauthenticated, and rate-limited generously enough that no startup will ever hit the ceiling.
X bills per resource: $0.005 per tweet read. Sounds tiny. Isn't. Per-resource pricing means a busy keyword is a money pump — my $4.37 afternoon was the pump working exactly as designed. (Posting is worse: a plain post is $0.015, but a post containing a URL is $0.20 — a 13× surcharge on the one thing a marketer wants to include.)

The two tricks that collapse the cost

After the $4.37 afternoon I rebuilt our X polling around two ideas, and I think they generalize to anyone building (or buying) monitoring.

Sample, don't drain. You don't need all 90 hourly posts from a firehose hashtag — you need the newest slice, scored hard. We cap each poll at 10 results. Quiet keywords are unaffected (you only pay for what exists), and firehoses get sampled instead of drained. With per-resource pricing, the request cap is the budget cap.

Back off when saturated. If every poll comes back full, the keyword outproduces your sample — so the poller doubles its own interval, up to a ceiling, and decays back when volume drops. A worst-case firehose now converges to about $6/month instead of $30. No human decision required; the founder just types the keyword.

There's a third trick that only works at the platform level: shared watches. If a hundred founders all watch r/SaaS, that should be one poll, not a hundred. Inside Thread Otter, every watch is a global object — the marginal cost of the hundredth subscriber to a popular community is zero, which is why we can include monitoring in a $49/mo plan that the suites charge $119/mo for. The economics aren't magic; they're deduplication.

What you should actually pay

My honest decision tree, having now lived all the branches:

Pre-launch, zero budget: F5Bot for Reddit/HN, done. Free, five minutes of setup.
You want broad web/news coverage and PR metrics: pay the suite. That's what they're for.
You're a founder whose buyers live on Reddit, X, and Bluesky, and you want mentions to end in sent replies rather than dashboards: the monitoring layer should cost you almost nothing — Reddit and Bluesky are free, X is controllable with sampling — and your money should go to the layer that actually saves your time: scoring, drafting, and the daily queue.

The mention firehose is a commodity in 2026. Anyone who charges you suite prices for the firehose alone is charging for the part that's free.