Somewhere in here was a mention of the hard-mounted bars on 04 and ups compared to the rubber-mounted bars of the pre-04 bikes.
If you want to rubber-mount your bars, all you need is a couple of washers and some hard rubber. I've done this on a few bikes over the years and it works fine on the Sportster. I use 30mm washers and the heavy-duty rubber tips (not plastic!) for walking sticks - both can be bought at a hardware store for a dollar or two.
Cut the rubber about 1/4" or so from the end of the tip and punch a hole in it slightly smaller than the width of the mount retainer bolt. You want this to be a tight push fit over the bolt. Take out both bolts and move the bars back to clear the holes, push one bolt through, drop on a washer, press the rubber 'ring' tip upwards onto the bolt and push it though about 1/2" and drop the second washer on. Do the same to the other side. You can then place the bar mounts on the bolts and do them up - the tight fit of the rubber will stop the bolts falling out while you do it.
Tighten them up until the bars don't move the bolts in their holes - probably about 4-5ft/lbs. You don't want them tightened hard down like a solid mount. For the first few days, nip up the bolt every day or so as the rubber compresses and the mounts start to move on the bolts. The tight fit of the rubber will stop the bolts from ever falling out, so there's no danger of the bars falling off - though you could drill and wire the heads if you are really worried.
That takes out most of the vibes on the highway, costs next to nothing and can be done in about 15 minutes. If you are really keen you can do the same to the footpeg mounts with some flat bar and 1/4" thick heavy rubber sheet. I haven't bothered on the Sporty, but I have done it on some other 'shakers'.