Anyone know if this is just a bouzouki with extra quartertone frets or some other thing?
Trinity College bouzouki, black top; see link below. TC is one of the Saga family of brands, who also produce Blueridge guitars and Kentucky mandolins among other instruments. i can find no evidence they ever produced a bouzouki with quarter-tone frets, so either it was customized (more likely) or they ran one up especially for him. the frets on Lindley's instrument look fatter than the ones on stock TC bouzoukis, so i suspect he had it refretted with wider frets and the quarter-tones added. compare to the Saga website.