I have to disagree with this:
At RETAIL, the cost of such a setup would be $106 million. Assuming that, to be theoretical, the US government wanted to launch an attack on bitcoin, they wouldn’t buy these units at retail and would indeed be able to negotiate huge price breaks from whichever supplier they chose. Lets assume that in that sort of quantity the final cost for a finished unit is 1/8th of what ASICMINER charges at retail; that means that the total cost that the US government would currently have to spend to upend the bitcoin network is only a hair over $13 million dollars.
ASICMiners production costs are not nearly 1/8th of their sales price. I'd guess their profit margins are 10-20%.
They couldn't just buy 130PH from ASICMiner or any other manufacturer because they just don't have enough chips and it would take at least a few months to produce more. (not to mention I don't think any manufacturer would support a government plot to 51% attack the network)
If the government wanted to design their own ASIC starting now it would take at least 1-2 years until they begin mass production and by that time $100m will barely put a dent in the network.