I hear you on the cost. They do however make claims around helping water quality and other things related to fish environment. I do also like the natural look vs. the look of a floating dock. But it does come back to the cost. That is why I was wondering if anyone here has used them or heard of them.
I also think that maybe something like that could be made with PVC and foam and a mesh layer of peat moss and hydroponics methodologies for a lot less than the $450. As for saving the money for adding fish, there is always money there for that

I just wanted to gain the benefits of a island while not eating up volume in the pond for an island.
The other thing I thought that a floating island would help with is that I currently have a floating board out in the pond holding my line to the aerator and I thought I could attach the island to that and kill two birds with one stone so to speak. Well I hope someone out here has some more thoughts on this and or has tried something like this in the past.