Costs, Budget & Timeline of AI Agents: Honest Numbers
TL;DR Budget
| Type | Monthly Cost | Build Time |
|---|---|---|
| No-code personal agent (Lindy, Relevance AI) | $20-80 | 1-3 days |
| Low-code small business | $50-300 + API | 1-3 weeks |
| Custom dev (LangChain / CrewAI) | $100-1000 API + dev time | 3-8 weeks |
API Cost Math (Real Example)
Agent that processes 100 customer emails/day, avg 800 input + 400 output tokens, GPT-4o-mini at $0.15/1M in, $0.60/1M out: ~ $0.0003 per email → $9/month. Same with GPT-4o: ~$0.005 per email → $150/month. Use small model for triage, large for final draft.
Hidden Costs People Forget
- Vector DB: Pinecone $70/mo starter, or Chroma self-host $0 but DevOps
- Observability: LangSmith / Langfuse $39+/mo
- Human review time: 30 min/day at start
Timeline
Week 1: Define 1 task + success metric. Week 2: Build tool wrappers. Week 3: Test 50 cases, add guardrails. Week 4: Ship to 10% traffic, monitor.
Budget Template (Free)
See our AI Agent Cost Calculator - interactive tool.