Please review Gazelle dot com

Please review the website and see the functionality. Essentially people go to this website and see what offers they can get for electronics that they have. This website uses real-time price quotes that they will offer for the item based on average selling prices on ebay.

1. I am looking to create a similar website and rebrand it. I need some ideas on how to pull the average selling price from ebay and offer a percentage on what it sells for. I know I can setup with ebay research api and pull the average selling price. http://developer.ebay.com/products/research/

2. Will require joomla or wordpress backend for easy updating. OR other if you recommend.

3. Need to figure out how to have the database of all the products and images so people can search for almost any electronic product. Phones and game systems are key categories.

4. Require the auto complete search bar.
I will need to have same products or more pulled into the website so people will be able to search for products. Need someone with experience that knows how to do this and be able to keep the products fresh and up to date.
Please bid and provide your qualifications.

Please do not apply if you do not have experience with creating site of this magnitude.