You are partially correct. What you see on Alibaba anyone can buy if they have enough money. Most of the cases require that you buy 900 at a time. The cases come in a plastic bag.
I've been doing this long enough to recognize the same designs made by the same factories for every phone that comes out. Most of the ones you can buy are garbage. Even worse they can sell the cases from China for $2 because China subsidizes shipping (.75 anywhere). Of course it will take a month to get to you but for $2 who cares.
That's why I said the S-Line cases were the joke of China. In a few months every single seller will have tons in stock and the price will plummet.
There are a few good quality manufacturers I found that make the same design for each phone but they are few and far between.
The margins for these cases are very large for one main reason - there is no mold fee. That's the fee to make a mold to create the cases with. Generally a decent mold costs $5000 and up.
So not every case you see selling is a high margin case - the ones that places like Seidio, Otterbox, Incipio, etc... have tighter margins because not only do they pay for the mold, but the cost per piece for quality materials is very high. Then throw in packaging and all the other costs and it's not as easy as it sounds.
This is why the Kiosks you see in malls selling cases do so well. They are owned by a large group who buys in size and ships a bunch of kinds to each Kiosk. The Kiosk hands you the case - no packaging needed. They get almost 100% of their cases from the stock china cases you see. So they spend .50 per case and sell it for $20. Kiosks are a bigger rip off than retail which is pretty bad also.
Also, Korea is a place that makes cell phone cases also. Much higher quality but a much higher price.
I have piles of cell phone cases here - most are garbage. Some of the ones I have are very nice and I've sold them before. But you cannot run a company selling products that are available to anyone.
It's not as easy as you think and not as high margin as you think when it comes to a high quality company who cares.
Also try to find an honest company to do the work for you... good luck.
Phone cases are an extremely high margin business and they are ALL made in China. Other than a few larger "manufacturers", most are merely sourced from China then branded.
Here's what you will basically see flood the market...
Galaxy S3 Cases-Galaxy S3 Cases Manufacturers, Suppliers and Exporters on Alibaba.com