What you'll need
Three accounts. Free or close to it.
n8n
Free self-hosted, or n8n Cloud starting $20/mo
OpenAI API key
Pay-as-you-go, ~$0.0002 per reply
Twilio
$1/mo for a number, ~$0.008 per SMS in US
5 to 10 of your past replies
Pasted into the system prompt so the model copies your tone
The math
What this is worth, conservatively
Inbound inquiries that arrive outside business hours
~30%
Lead drop-off when no response within 5 minutes
~15%
Recovering half of that drop-off on a 100-leads/mo pipeline
+7.5 leads/mo
Annualized at $300 average lead value
~$27,000/yr
Cost to run this template forever
~$24/year
Numbers based on Harvard Business Review and InsideSales lead-response benchmarks. Your actual results vary with industry, lead value, and how closely the AI reply matches your real voice.