at first if the cost is related with just for your code (VM)
or all Azure services you are using
since the service you are using is very advanced as you know TTS Avatar converts text into a digital video of a photorealistic human
The Azure TTS Avatar solution seamlessly combines several advanced technologies:
- Text-to-Speech
- Computer Vision
- Deep Learning
at first, you need to find on prem alternative for this service if you want to get rid of these costs but as i know there is no alternative for this service as an on-prem solution
if you just want to get rid of VM costs
you can deploy your code to your on-prem environment and connect your code to Azure TTS Avatar via API