Yes, both Microsoft Power BI and Dropbox Professional offer a Free Trial.
Microsoft Power BI is designed for Large Enterprises, Medium Business and Small Business.
Dropbox Professional is designed for and undefined.
Pricing for Microsoft Power BI Starts at $4,995/Month whereas for Dropbox Professional Starts at $9.99/Month when Billed Yearly.
Some top alternatives to Microsoft Power BI includes Google Drive, Tableau, IBM Cognos Analytics, Dundas BI, SAS Business Intelligence, Clear Analytics, SAP BusinessObjects BI, ibi Analytics Platform, Narrative BI and Microsoft Power BI Desktop.
Some top alternatives to Dropbox Professional includes CollaborateCloud, CloudFiles, Dropbox Business, FileCloud, ownCloud, MyDocsOnline, FilesAnywhere, DocUp, etfile and Dropbox Paper.