To understand the capabilities of these software, you have to put forward your requirements to their sales team. Have you defined your requirements already? Are open source softwares like EPANET and EPA SWMM unable to fulfill them?

Generally EPANET and SWMM are sufficient if used properly to understand main concepts required. The only advantage of purchasing expensive software are that they make the students market ready. To limit these costs, my approach would be, to start with EPANET at Uni, and then learn WaterGEMS if interested through relevant internships at companies. This will not unnecessarily burden the students with increased fees.