What will it cost to run this every day?
Renting a model's judgment has a price per run. Code doesn't. At one run a day the difference is invisible; at a thousand an hour it decides whether the thing is worth building. Put your numbers in.
What the three routes actually are
Model every run. The obvious shape: every item goes to a model, every run costs money. It is the right answer when every item genuinely needs judgment, and when volume is low enough that the bill never matters.
Cheap filter, then the model. Put deterministic code in front. Most items don't need a model at all — the page hasn't changed, the email is a newsletter, the field already parses cleanly. Code decides that for nothing, and only what survives reaches the model. This is usually the biggest single saving available to you, and it costs an afternoon.
Code the whole thing. Use a model once, while you're building, to work out the rule — then capture that rule as code. From then on it runs at zero marginal cost forever. This only works where the decision is genuinely stable: "has this number gone down", "is this field a date", "does this match the pattern we agreed". Where the decision is fuzzy and keeps moving, you'll be back to paying for judgment, and you should.
What the calculator doesn't price
Your time. Writing the code route takes an hour or an afternoon, and scrapers and integrations need maintenance when the thing on the other end changes. If the model route costs you $40 a year, it wins — your afternoon is worth more than $40. The reason to read this page is that the same task at real volume is often not $40 but $4,000, and that is the number people don't compute until the invoice arrives.