Well worth the $17. My heal/toe shifter doesn't bounce around and rattle like it used to. Not only nice for noise reduction but I have to imagine it'll help keep the levers from loosening over time which would result in spline damage or premature wear.
NOTE: After I put the spacer, spring washer, and levers on the splined shaft, I used a c-clamp to partially compress the spring washer and hold it while tightening down the shifter lever screws. Holding it by hand and tightening was a pain and it didn't quite get enough compression on the spring washer and the lever still wanted to rattle a bit.