20 devs/DBA/IT for 2 years would cost you something like 4M, 8M at max(Super Salaries for everybody) !
The costly part is the "Management" which creates the bureaucracy so other people can hang out in the project controlling excel tables while those 20 bastards work their asses off.
I don't think that includes consultants that helped the design, user experience, and architecture. Since they went with a pretty well known interactive agency, it probably cost them more than three million.
please add taxes and cost of workplace (office rent, equipment, etc)