Dear,
I already worked on similar projects.
I worked with bluetooth 4.0, i think it is best suitable for this.
I can do and mechanical design of cup, electronic and software for microcontroller. (all)
If software engineer work software for microcontroller then cut my price for 600$ so i will do it for 800$.
I have many propositions how to make this good way.
All the best,
Miroslav