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Part 6 of 7 · Packing slip checker series ~5 min read

What the packing slip checker costs

The only model call is reading a packing slip, and photographs are the main storage cost. Four hundred and fifty deliveries a month is a busy trade counter or a small distributor. Here is where each cent goes.

Key takeaways

  • About $407 a month at 450 deliveries. Roughly $1624 at 1,800 deliveries.
  • One Bedrock read per delivery is the only line that scales. Everything else is rounding.
  • Nothing is always-on, so a quiet month genuinely costs almost nothing.
  • Photograph storage grows steadily and is the line item to set a lifecycle rule on from day one.
  • 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 packing slip checker at three volumesA stacked bar chart with three bars, one per volume tier: 120 deliveries totalling about $109, 450 deliveries totalling about $407, and 1,800 deliveries totalling about $1624. Each bar is stacked from bands. The largest and fastest-growing is Bedrock, one read per delivery, 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$500$1000$1500$2000~$109.42120 deliveries~$406.92450 deliveries~$1623.981,800 deliveriesBedrock — one read per deliverySES — asks, results, receiptsS3 + 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 delivery — is the only part that grows; the orange fixed band is the same 86 cents at every volume.

Line by line

LineAt 450 deliveriesHow it scales
Bedrock read$405.00Linear. One call per delivery, roughly 1,800 in and 200 out tokens.
SES$0.23Linear. About 0.12 messages per delivery.
DynamoDB + S3$0.35Storage 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.

The read band is one packing slip per delivery. Messaging covers supplier notifications on discrepancies only, which is a small fraction of deliveries.

The three ways this bill surprises you

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

  • Storing full-resolution photographs forever. Two per discrepancy at phone resolution adds up. Resize on upload and move to Infrequent Access after ninety days.
  • Reading slips that arrive as structured data. Suppliers who send a file should be parsed, not read by a model. Check the format before spending a read.
  • Photographing every delivery rather than every discrepancy. A photograph of a correct delivery proves nothing and costs the same as one that proves something.

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. 120 deliveries, about $109. 450 deliveries, about $407. 1,800 deliveries, about $1624. 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~$1120 deliveries~$109450 deliveries~$4071,800 deliveries~$1624One 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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