I have uploaded another example here. It is a notebook that allows you to train your fast.ai model using SageMaker notebook instance then it shows how to upload the model to S3 and deploy as a SageMaker endpoint. You can deploy the endpoint locally to test as well.
There is no support for Elastic Inference with PyTorch models as far as I know. In any case you can launch an endpoint with a CPU based instance (instead of GPU). We recently announced support for ONNX models and the Elastic Inference. An example is shown here.