Uno and Arduino HID project

I am trying to do a feasibility analysis on a custom keyboard. I want to make a PC gaming keyboard for number of my friends for a game that we all play. This custom keyboard will use 6 or 7 trigger buttons only. This limited keyboard will send predetermined keyboard keys to the computer. I know that there are any number of replacement keyboard controllers that can be programmed to do this. But I want to use Arduino because that is what I have to develop with.

My goal is use an Arduino as a standard USB keyboard controller. I found many threads on topic of updating the flash of an uno or any other number of project boards.

What I can't seem to find out is what is the cost of doing so? Does this mean I need to implant the entire Arduino UNO board into the project?

It is my understanding that one of the strong points to Arduio is that the controller IC's are rather inexpensive for small production runs. Since only the Atmel chip is used in the final product.

I would rather not get to involved in this route if the minimum cost is going to be the entire Uno board + other parts, per unit produced.

Thanks for any insight.

Perhaps read about the Arduino Leonardo. It has the direct ability to act as a mouse/keyboard so you wont necessarily need to wire it into a keyboard. Read up on these:

Those links were somewhat helpful, but didn't really answer my question.

When the project is ready for production, in addition to the ATmega32u4 microcontroller, what other ancillary parts are needed for it to operate in USB HID mode?