Azure Stream Analytics. Pricing

As a cloud service, Stream Analytics is optimized for cost. There are no upfront costs involved - you only pay for the streaming units you consume, and the amount of data processed. There is no commitment or cluster provisioning required, and you can scale the job up or down based on your business needs.

While creating stream Analytics Job, if you created a Stream Analytics job with streaming units = 1, it will be billed $0.11/hour.

If you created a Stream Analytics job with streaming units with N, it will be billed $0.11 * N/hour.

Hope this helps. If you have any further query do let us know.

NO. You will pay only for what you use. For example if you configure 1 streaming unit and used 10 hours per month (10*0.11). If you configure 2 streaming unit and used 20 hours per month (20*0.11*2)

1.If i don't send any data to Steam Analytics I will be charged 80 USD a month for having the service deployed.

Quick answer is yes.Based on this document:

As a cloud service, Stream Analytics is optimized for cost. There are no upfront costs involved - you only pay for the streaming units you consume, and the amount of data processed. There is no commitment or cluster provisioning required, and you can scale the job up or down based on your business needs.

SU is basis of ASA job. Choosing the number of required SUs for a particular job depends on the partition configuration for the inputs and the query that's defined within the job.More details,please refer to this link.

2.Then op top of that I pay for my actual usage in form of streaming units, where a streaming unit, according to the FAQ, is a blend of compute, memory, and throughput.

If your data is not updated in real time, or very small,maybe ASA is not your Best choice. You could follow some suggestions in this thread:Azure Stream Analytics job expensive for small data?