To summarize the legal position of Xian:
The contract that Xian and BFL entered into was not a normal sale, nor was it a pre-order. Pre-orders involve either deposits or credit-card authorizations, but not the full amount (at least according to Amazon, Barnes & Noble, Ebay, Newegg, Best Buy, and Apple). If you order something that is not in stock, the online retailer will not charge your credit card until they ship the product. The contract entered into with BFL was called a foward sale.
An example of a forward sale is a farmer agreeing to sell soybeans a year from now to ADM for $540 a ton. Suppose that when the soybeans are finally ready the market price for soybeans is $800 a ton. The farmer is still obligated to sell them to ADM for $540. The farmer cannot legally unilaterally void the contract then refund the $540 to ADM and turn around and sell his soybeans to someone else for $800.
However, this is precisely what BFL did. They agreed to a contract to sell a specified amount of future units for a specified price. The market price of the contract rose five-fold. BFL then canceled the contract without compensating Xian for the fair market value. Finally, they turned around and sold the merchandise that Xian had rights to for more money to someone else (again via forward sale, but for a higher price than Xian paid).
Moreover, BFL does not support purchase of their products with credit cards. Why? For the simple reason that the credit card companies would not let them have pre-orders longer than 30 days, would not let them charge the full amount without delivery of product, and will come after them with lots of lawyers if they tried to do so.
The method of payment does not strike me as being particularly relevant to the issue of contract.
I would be hesitant to characterize the sale as a "forward contract". I would be inclined to characterize it as a sale of future goods (emphasis added):
Definitions--transferability--"goods"--"future" goods--"lot"--"commercial unit".400.2-105. (1) "Goods" means all things (including specially manufactured goods) which are movable at the time of identification to the contract for sale other than the money in which the price is to be paid, investment securities (article
and things in action. "Goods" also includes the unborn young of animals and growing crops and other identified things attached to realty as described in the section on goods to be severed from realty (section 400.2-107).
(2) Goods must be both existing and identified before any interest in them can pass.
Goods which are not both existing and identified are "future" goods. A purported present sale of future goods or of any interest therein operates as a contract to sell.