Creating an affordable colour detector

Hello there.
I am a totally blind user of assistive technology, and to that end I've always been frustrated with how expensive it is.
A friend and I are starting a business to develop some more affordable options. We are starting with a talking colour detector, priced at about $75 rather than the $175 maxiaids desires.
He is an engineer and hardware designer, and he's told me the sky's the limit on ideas. I have ideas of my own but i'm not going to put them here, to encourage thinking.
So I'd like to know, what would you like to see in a colour detector? A few questions to get you started:
1. would you like it to only tell you basic colours, or would you like it to go into shades and such?
2. Battery powered vs. rechargeable?
3. any features that you wish the current ones had?
Again, this is a hardware device, since the iPhone apps don't end to be super accurate.
thanks in advance!