VFP native DBFs could serve you application. Using Cursor Adapter class you can made you VFP front-end to work with DBF's, SQLServer, MySQL, Oracle,Sybase, etc. back-end.
Most of commercial frameworkcs http://fox.wikis.com/wc.dll?Wiki~FrameworkSalesMarketingInformation~VFP have very good multi-user with different user rights client-server support.
I suppose that you will have wonderful time during development of your product this summer. If you can risk you can start with VFP9.0 beta and in the autumn to recompile it in official version. In this case you will be able to gain from new reporting features