The Hidden Costs of Custom AI Agents: Build or Buy?

Building custom AI agents provides control but conceals substantial engineering costs in model maintenance and continuous evaluation. As LLM providers frequently introduce breaking changes—like OpenAI deprecating model versions and Anthropic adjusting rate limits—developers often face unexpected overhead, sometimes spending 40+ hours on single model migrations. This analysis reveals when building makes sense versus leveraging marketplace solutions that already handle these ongoing operational burdens.