Only when sold in a Apple store. Anyone else selling the product (by law) can place the product "on sale" at their discression.
The end result of that would be Joyetech would be "no more" in the US.
If I was a large supplier, I would file an antitrust suit in a heartbeat.
I'm afraid you're mistaken here. Apple is not a monopoly company. They don't make any product that doesn't have a competitor on the market. You can buy an Android phone, or a Galaxy tablet, or a Windows PC, so they aren't considered a monopoly. This gives Apple certain rights.
Apple makes a product. While unique in many ways, it DOES HAVE COMPETITORS. As such, they are allowed to put constraints on certain retailers. What this means in the US is that they are perfectly within their right to sell to whomever thy like, and they will choose to sell to retailers who will abide by their policies. This does not constitute price-fixing as defined by US law. If Apple got together with Microsoft, Google, Samsung, Amazon, and other major competitors and came to an agreement, this would constitute price fixing, artificially raising the price on products and defying the supply/demand curve. On a product you don't HAVE TO PURCHASE (such as food or gasoline or energy) this is usually a bad idea and usually ends up hurting the manufacturer, if they get away with it.
Because Apple is only attempting to control the price on their products, they do have the right to enforce "minimum advertised prices". If you are an authorized Apple reseller, and you choose to openly sell your product for less than Apple tells you, you will not be thrown in jail, and the ghost of Steve Jobs isn't coming to your house to spank you. You simply will not be sold any more Apple product to resell. You will no longer be an authorized Apple reseller.
There is nothing illegal about this practice, in the case of Apple or Joyetech. It's crappy, and I don't know if Joyetech is big enough (or considered important enough by retailers) to effectively pull it off. However, Crappy != illegal.
Oh, and I'm only picking on Apple because someone else brought it up first. Almost every major label in electronics does this (Alpine, JVC, Sony, Kenwood, Mitsubishi, Yamaha, Onkyo, etc.) as well as the fashion industry (Ralph Lauren, Tommy Hilfiger), and, I'm certain, many other industries.