I think scammers, even the ones in Nigeria, use a wide variety of tactics. I think it's prudent to be wary in a situation like this, where the OP is explicitly looking to offer services for money in an unusual situation in what will likely be an unconventional transaction.
Maybe this link will explain a bit more about my situation: http://en.wikipedia.org/wiki/Achromatopsia#Complete_Achromat...