Hi Hal, no, I hadn't seen those before, and it seems they're out of stock with no pricing available. I'd bet that with my R&D included, I've still spent less than those would have cost me. At least one of the reviews mentions that though working well, they seem somewhat expensive/over priced, for what they are.
And yes I use tape on the floor, but once the speakers are placed to my liking, they're never in exactly the same spot once lifted and placed on the isolators. A 1/2" here, 1/4" there, and they couldn't really be moved once on the early isolators I was using. Now I can make fine adjustments with the isolators in place.
I could be tempted to try the Herbie's offering, but I'm really quite happy with what I was able to develop on my own