Smells like a bargain.

Kurt Cobain’s guitar from the “Smells Like Teen Spirit” music video will be sold at a Midtown auction next spring — and it’s expected to fetch millions, The Post has learned.

The Nirvana frontman’s 1969 Fender Mustang will be put up as part of massive sale of the late Indianapolis Colts owner Jim Irsay’s music memorabilia by Christie’s in March, with an estimated sale price of between $2.5 million and $5 million, according to the company’s global president Alexander Rotter.

“He made the greatest music on this guitar and defined a generation,” Rotter told The Post of the Mustang, which is rumored to have been one of Cobain’s favorite axes.

“This is a piece of American history, so I [predict] a lot of people coming in for it … I am convinced it will get competiti

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