For a few days in March, Christie’s Rockefeller Center galleries felt less like an auction house than a public exhibition of 20th-century mythmaking. Fans came to see Kurt Cobain’s guitar, Jerry Garcia’s “Tiger,” and John Lennon’s piano from “Sgt. Pepper” and Ringo Starr’s “Ed Sullivan” drum kit up close. Then the sales began, and what had been a museum-like display turned into something louder, faster, and far more competitive. Across four sales, the Jim Irsay Collection brought in $94.5 million, making it the highest-grossing memorabilia auction ever staged. Every lot sold, with the cumulative take totaling nearly four times the low estimate. The series also set 28 world records.  Related Articles Many of those records clustered at the top end, where instruments and manuscripts tied to canonical figures in music and literature continue to define the category. David Gilmour’s “Black Strat” led the sale at $14.55 million, setting a new benchmark for any guitar at auction. Jerry Garcia’s custom-built “Tiger” followed at $11.56 million, while Kurt Cobain’s Fender Mustang from the “Smells Like Teen Spirit” video reached …