Great Britain gets a lot of things wrong, like food and spelling. But here's something they get right: They're willing to poach the best central bankers from around the world for the top spots at the Bank of England.

The UK is hardly alone on this. They're just particularly aggressive about it. Their latest target is Mark Carney, the current chief of the Bank of Canada. Before that, though, they snatched up American economist Adam Posen -- an expert on Japan's lost decade -- to serve on their monetary policy committee. You've heard of an international market for superstar soccer players and Olympic coaches. This is an international market for superstar central bankers.

It got me thinking: How much is a good central banker worth? Consider this chart. The blue line shows where our economy could, and should, be if it had kept growing at its long-term trend since 2008. The red line shows where we actually are. The difference between the two is the so-called output gap. (Note: These dollar figures are not adjusted for inflation).

We're in about a trillion-dollar hole. And that's a trillion dollars every year. Even if we get "Morning in America: The Sequel" and the economy rapidly reverts to its long-term trend, we'll forever be $4 trillion poorer than we would have otherwise been. 

Let's try a thought experiment. Say that Lars Svensson -- one of the world's top monetary economists and the current deputy governor of Sweden's central bank, the Riksbank -- could get our economy back to trend in half the time Ben Bernanke could. It's actually plausible-ish. Like Bernanke, Svensson spent his academic career championing unconventional monetary policy as a "foolproof" way to escape a liquidity trap. (Coincidentally, they were colleagues at Princeton). But unlike Bernanke, Svensson's Riksbank has been much more willing than Bernanke's Fed to experiment with these kind of heterodox policies. Perhaps unsurprisingly, Sweden's recovery has been the envy of the developed world. So I ask again: How much is a good central banker worth? Put simply, how much cash should we throw at Svensson to steal him away from Sweden?

That's another way of asking how long it will take the economy to return to trend. Here's where things get really depressing. According to Fed Vice Chair Janet Yellen, we won't get back to full employment until after 2018. If we assume the output gap will steadily shrink until then, that leaves us with roughly another $4 trillion in lost income. Maybe more. If Svensson really could double our recovery speed, he'd be worth $2 trillion to us. Even if that's being wildly optimistic, something on the order of hundreds of billions of dollars probably isn't. Tell me that wouldn't be worth paying Svensson a billion dollars a year. Maybe more.

The above suggestion is obviously a bit tongue-in-cheek ... but not completely. Right now, central bankers are paid almost entirely in prestige. Ben Bernanke is making just $199,700 this year. That's not to say that we need to pay central bankers more to attract the best ones. We don't. Economists really care about prestige.

This doesn't necessarily lead to the most efficient allocation of monetary economists. As Matt Yglesias pointed out, we'd ideally have economists prove their central banking chops in smaller countries before moving up to the big leagues of the Fed or the ECB or the Bank of England. Put a bit less diplomatically: Sweden is important, but it's a relative waste of Svensson's talents not to have him running a bigger central bank. (Not that I have anything against Sweden). Here comes the "to be sure" sentence: It wouldn't be enough just to import Svensson. As L.A. Galaxy fans can tell you, bringing in one (albeit, overrated) superstar like David Beckham doesn't help much if his teammates are only mediocre. We'd need to create a Federal Reserve board equivalent of the Super Friends for Svensson to make the biggest difference. We might even find out that we already have a superstar in Bernanke in that scenario.

Central banking should be a superstar profession. The difference between a top central banker and an average one can be astronomical, particularly when conventional policy is impotent. An efficient market would pay them accordingly. If the United States spent $10 billion assembling a central banking fantasy lineup of Lars Svensson, Stanley Fischer, Adam Posen, and Christina Romer, it would probably be a phenomenal investment. It'd pay for itself many, many times over. The biggest challenge is changing the norms around central banking. We shouldn't just consider the top American economists for the top spots.

We're a nation of immigrants. The Federal Reserve should reflect that.