Every AI use case eventually raises the same question: buy a purpose-built SaaS tool, or build the workflow on a general platform like Claude. Most businesses answer it by instinct, based on whichever option a salesperson happened to pitch first, rather than a framework that actually fits the specific task. This is that framework.
Four questions that decide it
How specific is the task? A narrow, well-defined, high-volume task (invoice OCR, appointment scheduling) often suits a purpose-built tool better than a general platform
How much does the workflow need to flex? A task whose rules change often, or that spans multiple systems, favours a build you control over a rigid SaaS product
What does the SaaS tool actually cost at your volume? Per-seat or per-transaction SaaS pricing can scale worse than a build with a fixed token cost once volume grows
How much does data portability matter? If the workflow's value is in accumulated context and corrections, owning that context outweighs a SaaS tool's polish
A worked comparison
A 30-person Melbourne wholesale distributor compared a purpose-built inventory-forecasting SaaS tool at $340 a month against building the same forecasting logic on Claude for a one-off cost of roughly $7,200. The SaaS tool won on speed to deploy (live in a day versus three weeks to build) but lost on customisation (it couldn't handle their specific seasonal-stock rules without a costly add-on) and on long-run cost (the SaaS subscription would exceed the build cost within 21 months and keep going indefinitely after that). They built, and by month 18 had recouped the build cost with room to spare.
Where buy is clearly the right call
Buy wins decisively for genuinely commodity tasks: accounting software, standard email marketing, anything where a mature market of well-tested tools already exists and your specific rules aren't unusual enough to need custom logic. Building your own version of a solved problem is expensive vanity engineering, not a strategic advantage, and most Australian SMBs don't have unique-enough accounting rules to justify a custom build over Xero or MYOB.
Where the framework gets it wrong if applied too rigidly
This isn't a one-time decision. A task that clearly favoured buy at 15 staff can flip to favour build at 50 staff, once volume and customisation needs both grow past what a generic SaaS tier comfortably handles. Revisit the decision as the business scales rather than treating an early build-or-buy call as permanent.
If you're weighing a specific build-vs-buy decision and want the actual numbers run against your volume, get in touch through /contact.
A middle path most businesses miss
Build and buy aren't the only two options. A hybrid approach, using a purpose-built SaaS tool for the commodity parts of a workflow and a custom Claude build for the genuinely specific parts, often beats either pure option. A Sydney logistics business used an off-the-shelf tool for basic invoice OCR extraction, which the market had already solved well, but built a custom Claude workflow on top for the business-specific step of matching extracted line items against their particular purchase-order rules, something no generic tool handled correctly out of the box.
This hybrid pattern typically costs somewhere between the pure-buy and pure-build numbers, and captures most of the benefit of both: fast deployment on the solved parts of the problem, and genuine customisation exactly where the business's specific rules actually diverge from a generic tool's assumptions. It's worth explicitly considering before defaulting to an all-or-nothing build-versus-buy framing, because most real workflows aren't uniformly commodity or uniformly unique across every step.
The question to ask before committing either way
Before signing a SaaS contract or greenlighting a build, write down specifically what makes your version of this task different from the generic version the market has already solved. If the honest answer is 'nothing much,' buy. If the answer names two or three concrete, specific rules a generic tool can't handle, that's the exact list a build needs to solve, and it's also the list worth pressure-testing against a SaaS vendor's customisation options before assuming a full custom build is the only path.
One more practical filter: check how many of your competitors or peers in the same industry are already using a specific SaaS tool successfully. A crowded, mature category is a signal the commodity option is genuinely solved. A category where every competitor seems to be building something custom is a signal your industry's specific rules may be unusual enough that a generic tool won't fit well either.
Keep the decision documented, even briefly, so a future review isn't starting from scratch. A short note on why build or buy was chosen, and what would need to change for the answer to flip, saves whoever revisits the question in two years from redoing the entire analysis from a blank page.
