In that case, I misunderstood you - my apologies.
A while back, FC said the chips would be priced between $0.49 and $0.99 per GH.
The price of a plug-in-ready miner is anyone's guess, depends who builds it.
Assuming the chips are cost $0.5/GH, ie aout $5 each, then a 2TH box will come in at a cost-to-build price of around $1600, or $0.8/GH assuming it has some form of internal heatsinking/fan arrangement and they give you a PSU with it. That's to get someone to assemble the bits, the chips take away $1000 of the cost, so if they cost $3 to make (?) then AM could in theory get systems for $400 less, around $1200 for 'internal' us. A third part supplier w0uld want to make a margin of at least 25% on selling their box, so getting anything under $1/GH is pretty unlikely.
25% margin is pretty high for such a competitive market. Using your number of a $0.8/GH total build cost for the assembler, different margins would produce different prices:
5%: $0.84/GH
10%: $0.88/GH
15%: $0.92/GH
20%: $0.96/GH
25%: $1.00/GH
So by adjusting your margin, you could easily get below $1.00/GH. And I imagine that the market is so competitive at the moment that margins should be on the low side.
Anyway, it's difficult to say what final prices would be, depends a lot on what kind of miners are built: immersion cooling blades, standalone boxes, rack mountable, air-cooling, liquid-cooling, etc. A lot of different possible design choices can be made, each with their specific costs.
Judging by the history the in stock miners were always overpriced while pre-orders had a lower price. If we add up shipping, customs and maybe PSU then the difference from 0.84$/GH to 1$/GH isn't so big as it looks when comparing 5% with 25%. Now(i know some people will be pissed)...if we look at my GB then we see that pre-orders for a company that already has launched products aren't flying off the shelf even at 0.83$/GH. Even if AM sells in stock miners for 1$/GH or less i still find hard to believe that there are people/miners/investors that are ready to spend ~100M$ for mining equipment in 2-3 months. In my view most of the money went down the hole of the fails and scams that ran for the last year. Now there aren't simply enough money, not unless the BTC price goes up a lot and very fast.