For me, at least $100, probably quite a bit more if I thought about it. However, I don't know that you could legally manufacture and sell/group buy such things. Nutraceuticals gets exceptions under the current, disastrous law but this wouldn't qualify.
If enough people pool in, you could underwrite your own clinical trial.
Why not? People have pooled-in to try drugs that are in development and not generally available yet. I can recall numerous instances: pitolisant, rintalimod, hyper immune IG, etc
Some went well, some were disasters, it’s the same as any other clinical trial.
People do group buys for all sorts of nutraceticals, small molecules, and even some biologics.