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Part 6 of 7 · Certification expiry tracker series ~5 min read

What the certification expiry tracker costs

Card registration is bursty and rare: a workforce of thirty registers most of its certifications in the first fortnight and then perhaps two or three a month forever after. The ongoing cost is almost entirely the chasing, which is email. Here is where each cent goes.

Key takeaways

  • About $2 a month at 60 cards. Roughly $3 at 200 cards.
  • One Bedrock read per card is the only line that scales. Everything else is rounding.
  • Nothing is always-on, so a quiet month genuinely costs almost nothing.
  • Registration is a one-off burst. After the first month the only recurring cost is the chasing, which is email.
  • The duplicate test runs before the read, so resends are free.
  • The three real risks: a retry loop, storage nobody expires, and a bigger model than the job needs.

The bill at three volumes

These are US East prices at the time of writing, at three volumes that bracket most small businesses. Find the bar closest to your own and read across.

Monthly cost of the certification expiry tracker at three volumesA stacked bar chart with three bars, one per volume tier: 20 cards totalling about $1, 60 cards totalling about $2, and 200 cards totalling about $3. Each bar is stacked from bands. The largest and fastest-growing is Bedrock, one read per card, in teal. Then SES for the messages, in pink. Then S3 and DynamoDB storage in green. Then a fixed orange band for Secrets Manager and AWS Budgets, which is eighty-six cents at every volume. Then a grey band for Lambda, SQS and CloudWatch. A note says the read is the only bar that grows with the business and the orange band never moves.$0$1$2$3$4~$1.3820 cards~$1.6960 cards~$2.71200 cardsBedrock — one read per cardSES — asks, results, receiptsTextract — both sides of each cardS3 + DynamoDBFixed — Secrets Manager, BudgetsLambda, SQS, CloudWatchThe read is the only bar that grows with the business. The orange fixed band never moves.
Fig 1. The monthly bill at three volumes. The teal band — one model read per card — is the only part that grows; the orange fixed band is the same 86 cents at every volume.

Line by line

LineAt 60 cardsHow it scales
Bedrock read$0.19Linear. One call per card, roughly 1,800 in and 200 out tokens.
Textract$0.16Linear at $0.0026 per card.
SES$0.04Linear. About 1.6 messages per card.
DynamoDB + S3$0.29Storage grows with what you retain, not with throughput.
Lambda + SQS$0.12Linear, and effectively free at this scale.
CloudWatch$0.16Flat, if you set retention. Unbounded if you do not.
Secrets Manager$0.40Flat. One secret, $0.40 a month.
AWS Budgets$0.46Flat. Two actions, so you find out before the bill does.

Textract runs on both sides of each card, which is why it is the largest per-card line. It is still under a cent, and it only happens once per card rather than once per reminder.

The three ways this bill surprises you

Every one of these has happened to somebody, and all three are cheap to prevent.

  • Re-reading on every retry. A card photographed in poor light may fail and be redelivered; keying the read cache on the image digest means a retry is free.
  • Chasing a lapsed ticket weekly, forever, by SMS. Email is free at these volumes and SMS is not. A ticket that has been lapsed for eight months and is chased weekly by text is a small but permanent bill for no additional effect.
  • Log retention left at never. This system does very little most days and will otherwise be almost entirely a CloudWatch bill within a year.

What it costs when nothing happens

This matters more than the headline number for a seasonal business. In a month with nothing to process the bill is the fixed band: Secrets Manager at forty cents, AWS Budgets at forty-six, and a few cents of storage. Call it a dollar. There is no instance to stop and nothing to remember to turn off.

The monthly bill at four volumes plus one failure modeA horizontal row of five boxes. Quiet month, about one dollar. 20 cards, about $1. 60 cards, about $2. 200 cards, about $3. And one bad retry loop, about two hundred dollars. A note says four of these are the design working and the fifth is a missing dead-letter queue.THE BILL, AT A GLANCEQuiet month~$120 cards~$160 cards~$2200 cards~$3One bad loop~$200Four of these are the design working. The fifth is a missing dead-letter queue.
Fig 2. The bill at a glance, including the one that is not a volume at all. A retry loop with no dead-letter queue costs more than every legitimate use of the system put together.
  • Management
  • Analytics
  • Front-end & mobile

Set these on day one

  • A dead-letter queue on every SQS queue, with a maximum receive count of three.
  • Thirty-day retention on every CloudWatch log group. There is no default that is safe.
  • An S3 lifecycle rule on the object prefix, tiering at 90 days and expiring at your actual record-keeping horizon.
  • Two AWS Budgets actions — one that emails at half your expected spend, one at double it. The second is how you find out about a loop in an hour instead of a month.
  • Provisioned concurrency: none. Nothing here is latency-sensitive enough to justify paying for a warm function.

Next: the same system drawn for engineers — service names, resource identifiers, IAM scopes, table schemas and the model id.

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