Is it the actual “red champagne” from Australia? They have a commercial variety they grow under that name that is meant to be quite good.
The “blood” they have is aka “red centre”. A cross I am told of finger and calamonsi. I have a few and have had fruit off of them. Certainly unique, but not worth their $100 price tag. I purchased two long ago when they sold for $45. They root decently well, but are very thin and rather hard to graft. Have an almost weeping habit. A little more zing than your average finger lime (although IMO finger limes aren’t very good in general)
This finger IMO that they’re listing now resembles Rick Red more than champagne, but wouldn’t ever really know for sure. The one I really desire is Crimson Tide.
I was able to source desert a while back from a friend but the graft eventually failed. However, being close with hershell has its perks. He claims he will have a few exotics available this summer at Madison. One being the Desert. So keep watch there!