Obviously, your question is best answered by antiUSSA or Grin&Barret, but I would like to give my .02cents guess on the subject. AntiUSSA and Grin&Barret, if I am wrong with my view on the subject,please correct me if I am wrong.
I don't think antiUSSA actually bought all 1000 rifles. He wouldn't actually think that 1000 people were going to order this LEGP in such a short time. In time, all 1000 rifles will be sold. It may take a year, maybe two. But that is 1000 rifles RR wouldn't have sold.
Castle Arms waits until they have so many orders, like 100-150 rifles, then places them with Rock River who manufacturers the rifles at the discounted price since they have such a large order at one time.
Castle Arms then gets a cut of the cost of the RR made rifle for being a "middleman" that helped Rock River's business by getting so many rifles sold. Rock River obviously wouldn't of made this many sales on their own.
Rock River probably didn't rush with getting the parts for the rifles as they didn't expect this Group Purchase thing to be that popular.
No one is getting screwed here. It is just that those who ordered this LEGP have to wait for the rifle in order to get it at a good price.
I am a fan of ArmaLite rifles myself. But with the budget I'm on, waiting a couple of months for a Rock River Arms rifle at $660 versus a similiar ArmaLite rifle at $900, I'm going with the LE Group Purchase.
Also to add, the LEGP is not just another rifle. It is a "Limited Edition" rifle that only so many people will have. This by itself is worth having the rifle.