Hi there,
Interesting idea, but don't you think that this could be already be done by means of a J2ME application on a mobile phone? Phones already have bluetooth built in, colour displays and support the OBEX push profile that is used to transfer business cards between devices. Why carry around another device when almost everyone has a phone already? I would be able to write such an application for you.
If you still wish to produce a separate device then I can help you with this too. I am currently developing a device that has a bluetooth connection and a colour screen with a simple user interface so I am familiar with the technology. The value of the above bit will have to exclude all of the development environments, tools, sdks, manufacturing costs, license fees (where appropriate), certification, etc.
Contact me via the private messages if you would like to discuss this further.