Yesterday I found a pair at a garage sale for $10. They were from a Fat Boy rather than a Dyna, but getting the brackets to work wasn't all that bad. A huge reduction in sound, and a lot more pleasant to ride. No significant change in power.
I also fixed my trip odometer--the middle digit wasn't resetting properly, and there was a screw loose inside the spedometer. Getting the odometer working was fairly easy--the difficulties were in getting to it, and then getting the oil out from the places it shouldn't have been. If I ever do that again, I'll wrap the rest of the speedometer assembly in towels or something, to minimize oil getting where it shouldn't be.