Voiceover for screencast videos

I have around 9 screencast videos (and growing) each one around 1-2 minute duration. I am looking for someone to provide a professional quality voiceover. The screencasts are for a product demonstration. Hence you should sound as if you are demoing the product. I can provide the script if needed; the videos have text captions so should be easy to understand the context.

Please provide me your quote as well as samples to your past work. Deadline is one week.