There is always a trade-off between cost and batch execution time. It's possible to launch a small cluster and limit the data per batch and run it successfully. However, there is a chance the Streaming workload will develop backlog. So choosing the right cluster size is important and the prime factor deciding the sizing should be SLA for data availability rather than cost. but if the cost has more precedence then launching a small cluster will help.
As you are doing an aggregate operation, it can involve state management as well. If so, choosing the best state store can also help to reduce unnecessary costs on Disk expansion.
As @Kunal Gaurav mentioned, you can plan to run multiple streams on an interactive cluster. However note that Streaming applications can be long-running and because of the fact the on-demand clusters are cheaper, running the workloads on an on-demand cluster could be cheaper.
