The real question isn't cost — it's fit
SaaS products are built for the common case. That's exactly what makes them fast to adopt and exactly what makes them frustrating once your process diverges from what the product assumes. Custom software removes that ceiling, but it means owning the build and its ongoing maintenance.
When SaaS is the right call
If your process is genuinely standard — accounting, generic CRM, common HR workflows — an existing SaaS product has likely already solved it well, and rebuilding it from scratch rarely makes sense. The advantage of SaaS is that someone else carries the maintenance, updates, and infrastructure burden.
When custom software earns its cost
Custom software makes sense when the process you're running is specific to how your business actually operates — a workflow that would require constant workarounds inside a generic tool, or a business model no off-the-shelf product covers well. It also makes sense once you're paying for and stitching together several SaaS tools that a single connected system could replace.
The hybrid path most businesses actually take
In practice, most growing businesses run both: SaaS for the genuinely standard parts of the business, and custom software for the operational core that actually differentiates them. The mistake is treating it as an all-or-nothing choice rather than deciding function by function.