1. They have had people working on this game for about 4 and a half years. obviously it was a very small group at first then after fallout it was a large group..After all its expansions all the devlopers were working on Skyrim.
With most AAA games no one spends as much time as bethesda does on games.. Look at COD games They take not near as much time yet they still make more money than SKYRIM.
2. The voice actor list is out of this world and those actors had to have gotten paid a good amount of money.. these actors include Christopher Plummer, Max von Sydow, Lynda Carter, Joan Alien, Michael Hogan, Vladimir Kulich, George Coe and many many others this info is at this http://gamesas.com/eng/news/pressrelease_2011-0927.html
3. The size of the game world takes intricate detail especially on the PC version as well as the amount of man power it takes to create these massive interactive worlds with radiant AI.. That stuff takes a lot of development time
Anyone have any guesses as to what the Budget is or any other examples of how its expensive or cheaper?