In a previous life I represented an importer of Pro Audio & Lighting products (gear used in concerts, nightclubs, etc), most of which came from China. Before bringing a product to market we would go through a large number of sample prototypes to make sure they got everything right and met local codes. We would ask them to fix one thing, they would cut a corner on another. Meanwhile, we are paying for each sample, none of which could be sold. Our warehouse had a large area set aside to hold the prototypes that were really just garbage, but that the owner couldn't bring himself to throw away. Once we finally got the product right, it was time to buck up (as Merritt said, cash is king), then wait 60 to 90 days for the container, and hope that you got what you approved.
One of my dealers here in Vancouver thought that they could do better by buying direct from China. They were asian dudes, with family from Mainland China and Hong Kong, and thought they had all their bases covered. When the container arrived, most of the product had been destroyed in transit simply because they didn't specify they packaging. Yes, even the packaging needs to be specified.
There are some protections available here in Canada anyways, but for the most part you need a team that is looking out for you. China has a whole other way of doing business, and navigating it isn't as simple as it may seem. Unless you have a substantial cash reserve that you are willing to lose, I would suggest you rethink your plans.