Should we build or buy an SI solution?
Build an SI solution when the capability is core to how you compete, depends on proprietary data, or must meet control requirements a vendor cannot; buy when the need is common and an existing product already does it well. A sound decision compares three options, not two: a custom build, a SaaS vendor, and an open-source base you adapt. For each, assess total cost of ownership across several years, including inference, maintenance, staff and switching costs, rather than the first-year price. Check the capability gap against your actual requirements with a bake-off on your own data instead of vendor demos. Weigh integration complexity with existing systems, data sovereignty and where data is processed, and compliance needs such as GDPR ready data handling. Consider lock-in: who owns the prompts, evals and fine-tuned weights if you leave. Sometimes the right answer is neither, because rules or plain search would do. Capture the reasoning in a written memo your board can review.
