If Motorola and Cisco and other big tech firms have no trouble producing ASICs, why would the NSA? You don't need to fab them yourself, you just need designers and a fab partner.
When I worked for one of these orgs, we had a PowerPC rad hardened device which was based on a 603 and that was nearly $100k a unit in quantities of 50 and that was an off the shelf design. The one ASIC we had which was mixed mode (analogue front end and digital back end) was $25k a pop in quantities of 1000 on top of tooling and design costs of $7m.
Just doesn't add up. If its on the ground or can be bought in milspec form, it'll get used. Altera/Xilinx do this for a reasonable spend. Expect to be killed by an FPGA I programmed one day :(