It varies widely. Ballpark is 8 figures for a big-budget ("AAA") title these days... i.e. 10 to 100 Million (US $). But a lot depends on how you count, and there are tons of exceptions.
Here's a good way to guesstimate:
1) How many people on the team? A small team is around 20-30 people, large team would be several hundred. Look at the credits of a few games you own (either on the Credits screen from main menu if there is one, or in the back of the instruction book... or just check www.mobygames.com).
2) What was the length of development? Typical range for AAA development is 2-5 years.
3) Where was it developed? Games made in San Francisco are going to cost more in payroll than those made in Denver. Look up the IGDA Salary Survey, adjust for cost-of-living of the area, and cut it by a small amount because the Salary Survey is slightly inflated.
If you have a particular kind of game in mind, find some similar games (same genre, comparable production values) and you can probably research all three of the above things for a similar title.
Then, multiply: size of team (number of people) X length of development (years) X average annual developer salary ($/year). That gives you the baseline development cost in payroll.
Example for a small game: 20 people X 2 years X $40K/year = $1.6M
Example for a large game: 200 people X 5 years X $60K/year = $60M
What about other "operations" costs (office space, computer hardware and software, electricity, payroll services, etc.)? Ballpark, estimate those as 25% of the total dev cost, with payroll being the other 75%. So multiply the above figure by an extra 4/3 to get the final dev cost estimate.
If you want to include publisher costs (manufacturing, distribution, advertising), ballpark that as equal to the dev cost, so multiply your figure by 2 to get the final total cost of a game.
Hint: next time you hear someone complain about how video games are so expensive because they cost $60, remind them that the little package in their hand cost a lot more than $60 to develop :)