http://en.wikipedia.org/wiki/Buck_Rogers
Note that there were efforts to save money in the early movie serial.
That's true of pretty much all those movie serials. They relied heavily on stock footage, stock music, and the like. The reason Batman didn't have a distinctive Batmobile in his '40s serials was so they could reuse car-chase scenes from earlier serials. In the first Green Hornet serial, IIRC, different groups of bad guys kept holing up at the same abandoned house so that they could reuse the set. As for music, I think the Flash Gordon serials relied mainly on Franz Waxman's score to The Bride of Frankenstein.