Android App for Modbus Serial Communication $10

I need an android app with source code, for serial communication using Modbus over serial. I only need 4 pages with 2 commands, 1 to read the data and 1 to write the data. This app will communicate via Modbus over Serial or your can use Serial communication and convert the data to the readable form. I can provide the documentation for the protocol. The budget is only $10.