I am agnostic on whether cable risers make a difference. Therefore, I would not spend a lot of money on cable risers, especially since my basement system does not have appearence rules set by my wife. That said, a few years back, an audio buddy ordered a bunch of thick foam cut into keystone-shaped pieces. They are ~5" high, and, I would guess, offer some vibration isolation. They were cheap enough that I bought them. IIRC, I think they were about $10 for a dozen of them. So, I use them, but I have never really spent the time to try and hear if they make a difference or not.
One post did catch my eye, though: chazro mentioned that he had coiled some speaker wire due to the length being longer than required. While I would not argue for unequal cable lengths, you should never coil speaker wire (or any wire, AFAIK), because the coil will act as a resistor(?), and reduce high frequency through-put. I had been making the same mistake after I moved my amp from my equipment rack to be closer to the speakers. Some audio buddies of mine saw that, and one asked "do you feel your highs are too rolled off?" I said, as a matter of fact, I do! And he said "that’s because of your coiled speaker cables." He proceded to shorten my speaker cables. Veils were lifted. Highs were extended. The Soundstage widened. Unicorns flew over rainbows that arched between my speakers. YMMV, of course.