When I compare total pricing for a Voice AI in Livekit/Pipecat vs. VAPI/Retell I don't see the point of going with Livekit or Pipecat as it looks like the prices I would pay for SST, LLM and TTS in VAPI/Retell are better compared to what I would pay directly to e.g. Deepgram, OpenAI and Elevenlabs via Livekit/Pipecat. Even when self-hosted. Am I wrong?