Hi,
Can you please share your complete project requirements/task expected from us.
There are readily available boards <50$ with a battery option, programming, and around 50mm Dia.
What addition features are we trying/required to implemented.
About us:
Micro-controllers we have worked on PIC, STM32, PSOC and AVR.
Development kits and instruments available for testing purpose.
For PCB designs we use KICAD.
C#, LABVIEW, Python for GUI, Controlling or Datalogging purpose.
Thanks and Regards,
Santosh