People are jumping all over this, but I did read some more level-headed discussion of it somewhere (slashdot?). We don't know what the 1.4m covered. Did it cover procurement and installation of all of the ipads and custom mounts/stands? 150+ airports with TSA precheck, assume each has 2 precheck lanes and that you can get an ipad+mount+installation for $1000...and you're already at at least 300k
Training of staff? yeah yeah, easy job, but how many security line workers are there in america? (and remember, these are TSA workers here...they need a little extra help).
Add in 10 layers of planning exactly how the system works (Is it actually safe to randomly let X% of people through? How do we handle families? What about non-related travel companions?) and 20 layers of government bureaucracy/testing/approval...and you've got a big chunk of money.
Not that that is a great thing that they spend a bunch of money because of this, but I saw plenty of people saying things like "I'd charge a normal person X to write this, a large corporation X*2, and the government X*4 because I'll have to do twice as many iterations and provide twice as much documentation along the way". So I don't know that we can really fault the TSA for being confined to the government process. And they went with IBM...who you know are never cheap, and will definitely know how to milk a contract for money...but aren't some total hacks that will spend 6 months working on the project before they realize they don't even employ any iOS developers and need to hire one before they can do anything further.
edit: and FWIW, I think the whole thing is stupid and that everyone should go through precheck style screenings at maximum.