Hi Anand,
as @az38 wrote, it is very complicated.
Just some starting points:
1. "On Premises" (even if you want to use it in Azure)
With SQL Server EE with SA you get the right to use Power BI Report Server.
You are talking abount "all the functionality". Power BI Report Server doesn't provide "all functionality", but is a little bit limited: https://docs.microsoft.com/en-us/power-bi/report-server/compare-report-server-service
You didn't say whether you need SQL Server anyway.
I guess it is too expensive if you buy it only for getting Power BI Report Server.
If:
- you need SQL Server anyway
- don't need the functions that are available only in the cloud
- have even many Power BI users but using not too much capacity
(Report Server needs to be on same box as SQL Server
-> if you need a bigger box you need to enlarge the license)
-> then SQL Server EE SA could be a cost effective way
2. Cloud; a) PRO b) PREMIUM
Here you can choose from the user base model Power BI Pro (10 USD / user) and the capacity based model Power BI Premium with again higher functionality (starting at about 5.000 USD).
https://powerbi.microsoft.com/en-us/pricing/
With a low number of users, probably Power BI Pro has lower costs or is realistic at all. Again it depends on which functions you will use.
May you tell us a little bit more about your situation?
Regards
Michael
