I did reach out to flextank and ask about the winemaking tankerstein product they are working on. She said the costs will be comparable, but they don't expect the product to be out for a couple of months.
How do flex tanks work? I understand there's some sort of membrane on top of the wine. I've looked at their website and youtube and such, I'd like to see a video of how the wine is sealed off from oxygen (like if the tank is 3/4 full)