If only there were an app to nail black-market extortionists.

A cutthroat Asian group has set its crosshairs on the flagship Apple store on Fifth Avenue at 59th — scoring nearly every iPad 2 it can get its hands since the hot gizmo went on sale last week, to re-peddle at exorbitant prices here and in China.

The illicit, highly orchestrated scheme was in full gear yesterday, with a ringleader doling out massive wads of $100 bills to about five cohorts.

The sidekicks then went up and down a line of about 200 Asians outside the store and around the corner, handing out the money.

The scammers in line then went inside and bought iPad 2’s — wiping out the store within minutes.

“We buy from here, then sell,” one of the organizers gloated outside the store, standing near one of several bulging, oversized shopping bags filled with the hot devices.

“The ones we bought today are already on their way to China,” where they haven’t gone on sale yet, said the boss. “It’s been pretty crazy.”

When asked how much it would cost to buy a top-of-the-line iPad 2, which retails for no more than $829, one of the rogues demanded more than twice what it was just bought for — $1,700.

Then, his boss jumped in — and said it would be “best if you bring $2,000.”

An Apple worker inside the store said he didn’t like what was going on — but he couldn’t do much about it.

“Listen, we all know what’s going on here. I find it sad and disgusting,” the worker said. “These people are preventing ordinary folks from getting their hands on an iPad.”

A legitimate would-be customer said she’s been to the store three times since Friday — only to be thwarted by the creeps.

“I walked right up to the guy with all the bags and said, ‘Shame on you,’ ” said the woman, a Manhattan event planner who asked that her name not be used for fear she would be blackballed by the store and never get her iPad 2.

“He just laughed at me,” she said.

“I talked to the manager at the store. I said, ‘They’re dealing them right now upstairs on private property.’ . . . They said, ‘There’s nothing we can do.’ ”

Apple did not return calls for comment.