Hello Midhun,
As Mike indicated,there is no need to buy Work Manager or Inventory Manager applications to build custom application on SAP using Agentry. You need to install "Agentry SAP Framework Foundation" add-on in SAP backend which contains all core framework required for building custom application from the scratch which is part of SMP SDK. All the business suite mobile application are bundled into a different Add-on which you install when you buyMobile applications like Work Manager or Inventory Manager. Once you have "Agentry SAP Framework Foundation" add-on installed in the backend you build config panel entries for custom application.
Please refer to this posting How-to Build an Agentry based mobile app from scratch connecting to an SAP back-end Part1 ( http://scn.sap.com/docs/DOC-47550).
Thanks
Manju.
SAP Mobility - RIG