To design an ASIC you need a software which is expensive and you have to be really good specialist. It might not work otherwise.
In principle you can do the design for FPGA first and then reuse it unchanged for an ASIC. I think you can do that with just open source software. You do probably need an EE graduate with a specialisation in microelectronics.
And you need MILLIONS of dollars worth of equipment, not billions.
Depends on the size of the plant I guess, which would likely be small since you don't need to produce hundreds of millions of units. But fabs costs more than a billion dollars.
Companies, would not produce these miners because they could be adjusted for cellphone interception. The cellphone code is just 56bit. If you have a rainbow table it goes down to 36. You can imagine how easy would it be to get 10 of these devices and then decrypt conversations in real time.
By that logic Avalon, ASICMiner and BFL could not have found suppliers.
And there is another issue - banks are not going to be happy that big companies are promoting a decentralized currency. It's just the way they work.
That hasn't stopped the three ASIC mining companies.