If it is simply an "idea" at the moment, there are likely to be a multitude of variables which will be subject to change throughout the process from design, to full production.
Basic operational requirements such as user input method, display method, transmission protocol, operating voltage, current consumption, PCB dimensions, overall device dimensions, ROHS conformities, et al, need to be stipulated in a RFQ to an engineer.
The initial "I want a 'XXXXXXX' device which the user inputs and stores information via Up, Down, + & - push buttons in a menu, with the information displayed on a 2X16 character LCD, communicating over RS232, powered by a 12V Wall-wart, in a 2"X4"X4" enclosure." can quickly change into "I need a 'XXXXXXXX' device which the user inputs and stores information via an encoder wheel, with the information displayed on a 128X64 GLCD, communicating over USB and having the capability to run on batteries, or mains power, in a 1.5"X3"X3" enclosure." as the idea evolves.
Assuming the initial project is accepted as a paid job, some seemingly small changes, to the designer, can have a significant impact to overall costs from the engineering/programming point, due to PCB re-design or firmware re-writes etc.
As Bill advises, post your specs/project outline here for review.
You'll likely get plenty of help for free.....