Custom eCommerce Website Design and Coding

Hello I have a new ecommerce project I need coding into a shopping cart of your choice - whichever will work best. OSCommerce, CubeCart, OpenCart, Magento are all acceptable - whichever provides the flexibility to do what I need You will first code the PSD into XHTML/CSS and then integrate into the chosen cart Please bid and I will send you a preview of the home page (jpeg) to give you a better idea. Stage 1 - they will choose the type of product from the drop down menu Stage 2 - they will choose the width and height from the drop down menus -> price worked out based on height and width of product for example up to 7 foot high and 7 foot wide is £500.00 7 foot high and 7 foot 5 inches wide is £550.00 8 foot high and 7 foot wide is £540.00 (these are just examples) Stage 3 - they will choose whether they want automation -> if yes price added Stage 4 - choose the finish -> different price added per finish Price is calculated dynamically as shown on the front page and then they can click Buy Now to add to cart and go to to the checkout Could you let me know your preferred cart system, how the above will work and how long it could take Please show your past ecommerce projects Thank you