- "Justin Beiber case" => warning: you can't use people (or pictures or cartoon or...) images like that... and the rights can be pretty high
- "$1 cases for ~$10" => didn't you forget taxes, delivery, lost,... business is not: sell $10 - buy $1 = profit $9
Well... I think you should take a look at the business side
Your customers will not want to wait for their phone case for 8 weeks. Shipping phone cases one-by-one from China is obviously out of the question as well.
You also need to buy the Justin Bieber rights, before taking orders.
Also do not forget to setup with a fulfillment partner. You do not want to send out 1000 packages yourself.
Having $9 per case to work with is not too bad. Depending on the costs of the shipping (china+fulfillment) and licence, the numbers might still work out.
But I am not too sure on the advertisement side of things. A customer might be too expensive.
I buy stuff this way, typically when I don't need it urgently. I've bought phone cases, memory cards, small electronics — they have to be under €10, so they don't incur a customs charge. [3] Delivery often takes a month (by ship), but sometimes I'm lucky and it's just a few days, presumably there was space on a plane.
The competition is the 95% of sellers based in the US, who are selling the same cases for $10 with much faster delivery. [2]
The idea seems to rely on people not shopping around, since
[1] http://www.ebay.com/itm/Justin-Bieber-Cute-Hard-Phone-Cover-...
[2] http://www.ebay.com/bhp/justin-bieber-phone-case
[3] https://en.wikipedia.org/wiki/Low-value_consignment_relief
For anything you want to build and sell, you need to make sure that you (a) have a market, (b) can reach the market (marketing).
Again, it may not be completely right, as you may feel (as I do) that you are misleading customers a bit.