While the true cost of the Games is uncertain, analysts say the short-term economic benefits are likely to be minimal, a conclusion which puts the price tag under grater scrutiny.
The organisers point however to the "legacy" of the London Olympics -- the once-in-a-lifetime opportunity to transform one of the poorest areas of the city by hosting the world's biggest sporting event there.
Officially, the budget for the Games is £9.3 billion ($14.5 billion, 11.6 billion euros), a figure set in 2007.
That is already almost four times higher than the tentative figure given in 2005 when London won the right to host the Olympics.
In mid-June, the government said a contingency fund of £476 million remained in place to be dipped into for unforeseen emergencies.
But a parliamentary watchdog estimated in March that the Olympics were in danger of exceeding their construction and operating budgets, with the total cost to the public purse closer to £11 billion.
The focus of the Public Accounts Committee's concerns was how the original security budget of £282 million was doubled to £553 million.
Committee chairman Margaret Hodge said it was "staggering" that the original estimates were "so wrong".
Olympics Minister Hugh Robertson hit back, saying the calculations were biased.
The debate about the budget is not likely to go away once the Games are over.
Julian Cheyne of Games Monitor, a small but vocal citizens' group that is researching the cost of the Olympics, said the budget has been "fudged".
"The new budget of £9.3 billion is a complete fantasy, it does not include things such as acquisition of the land," he told AFP.
"And much of the money that is going to be spent on national security in Britain will go on the Olympics. I would suggest the real security budget is around £1.5 billion.
"Any time you have an infrastructure project of this kind, the budgets normally expand, but all sorts of claims are made in terms of what the Olympics are delivering that are simply nonsense.
"Basically, Stratford was a working industrial area that was already regenerating anyway before the Olympics came along."
Even if the final budget for London does reach £11 billion, it will still be only half the estimated cost of the 2008 Beijing Olympics.
The government has taken care to stress that rather than try to compete with the huge scale of China's "coming out party", the London Games is using many temporary stadiums that can be re-used elsewhere later.
Even the main Olympic Stadium in Stratford has been designed to have its 80,000 capacity reduced to 25,000, although a future tenant has yet to be found.
There may be efforts to cut costs, but even in challenging economic times, no modern Olympics can replicate the so-called "Austerity Games" held in London in 1948, three years World War II ended, when some teams brought their own food.
While the lion's share of the budget comes from the government, the organisers of the Games, LOCOG, have raised around £2.1 billion, from ticket sales and blue-chip sponsors such as British Airways and BP.
But will the Games have a lasting long-term effect on the British economy?
Capital Economics analyst Samuel Tombs shares the cautious view of many analysts.
"The example of past Olympics suggests that the legacy benefits of the Games are usually smaller than expected," he said.
"All in all then, while the Games will undoubtedly be a great sporting event, we doubt that they will win any gold medals for the economy."