Hi, as you can see from my profile, I have a lot of experience with Chrome Extensions, and many of them are similar to yours - they include a lot of scraping and automation. So I'm sure I can help you with your project.
It would be good if you can give me the links to your and your supplier's websites. Also, when creating order on supplier's website, how is finding a product carried out? By some unique identifier or through search? Also, I assume you already have created PHP interfaces, and I will have only to provide data to be sent to them.
Regards, Stefan