Augmentative and alternative communication ( AAC)

AAC is a broad term for forms of communication that supplement or enhance speech, including electronic devices, picture boards, and sign language. So my initial search into this area gives me an impression that there are lot of tools out there, may not be perfect and may also be expensive.
A Good start was at http://uk.dynavoxtech.com/ Their website states "As the world’s leading provider of augmentative and alternative communication (AAC) products and services, DynaVox Mayer-Johnson offers complete solutions for individuals with speech and learning challenges. Our speech devices help those with conditions such as autism, MND, cerebral palsy, stroke, brain injury and others; make meaningful connections with the world around them."
I could not find much in terms of the cost and availability outside UK. I have sent them a message and will will update on receipt of response. The gadgets look good, but there was no demo online and the flash demo was too slow for my patience.
I did find another site http://www.touchntalk.com/ . A touch enabled software for windows. More on it later