Ok, so french is a lovely language... But I guess I will have to write this in English, I hope you dont mind.
An OSCommerce to Magento migration is a very wise call. I would love to do it for you. I see you are new here or at least have no reviews, so will also imply you have received a bunch or oriental bids. Fortunately, this one you are reading is the real one. I have done great magento stores for italy, russia, england, usa, germany and you can have a great result too. I was in charge of creating 80spurple, ernestalexander, fashionara, navali, shopbop, shoelook and many others. Turns out ecommerce is my life.
Well, if you are interested in some west based company, I'd be glad to discuss terms and details.
We provide a better timezone, convenient English communication and a deep occidental understanding of business. Together with a crystal reputation and ecommerce experience as old as html we are the best choice for this project.
I hope you are interested, thanks for your time.
Best Regards, Emiliano