Sept 30 (Reuters) - As fans readied to see how chemistry teacher turned drug kingpin Walter White would meet his end in the tense finale of "Breaking Bad" on Sunday night, one Albuquerque donut maker had a rush of customers on her hands.

"It was insane," said Carrie Mettling, the co-owner of the city's Rebel Donut chain, which sold $10,000 worth of its blue frosted and crystal rock candy-slathered "blue sky" donuts in the hours before showtime. "Our sales were probably quadruple what they are on a normal Sunday."

The local business is among many in the wake of the runaway success of AMC's "Breaking Bad" - a show both set and produced in Albuquerque, New Mexico - whose profit margins have been so good lately they are almost criminal.

The chain, whose donuts are named for Walt's top-notch "blue sky" methamphetamine, is among several Albuquerque businesses that have felt a rush to their bottom line with the success of the Emmy-winning show

"Breaking Bad" has enjoyed a surge in viewers in the past year, as an average of 5.2 million people tuned into the last half of the fifth and final season to see cancer-stricken Walt complete his metamorphosis from a mild-mannered high school teacher to the murderous drug kingpin known as Heisenberg.