Animated video promo for landing page

I am looking for a quality animated short promotion video for my web page. I have not nailed down the length but it will be roughly 45 seconds (+ or - 15 seconds). An ability to provide your own creative input is essential. However, I will likely be heavily involved in the process and would like to be able to provide feedback multiple times during the videos creation. I will provide a script, and creative direction for some of the scenes, but again I would like creative input filling out the time. If you can provide high quality audio/voice let me know but I can provide music and audio which I will also need added to the video. I would like to discuss with the winning bidder how to integrate the audio and whether I should have it produced before/during or after the video is being created so the timing is correct. I want the video to be colorful followed are some examples of animations I like: [login to view URL] [login to view URL] Please provide examples of your 2d animation work. Note: I will not pay upfront. I'd like to see some progress before paying anything. And will only pay the bulk of teh fee after completion. Thanks! I look forward to working with one of you!