Is buying always the better first step?
No. Buying is the better first step when the workflow is standard enough and the product already solves the right job. When the bottleneck is highly specific, buying can create a false start.
Is custom always more powerful?
Only if the workflow justifies it. A custom system is not automatically better if the team is reinventing a common pattern that mature software already handles well.
What is the best way to decide?
Map the actual workflow, the required data and system actions, the operator path, and the places where generic tools fall short before making the decision.
What usually triggers the shift from buy to build?
Teams often start with a bought tool, then move to a custom build when the highest-value part of the workflow still requires too much manual handling outside the product.