The answers to your questions are probably best summed up as follows:
- Never buy BAC water (or any injectable) on Amazon.
- The entire "Research Use Only" disclaimer is legally dubious "cover" for selling these types of products.
- "Made in the USA" claims for "Research Use Only" products are 99% lies.
- There's a better than zero chance that any BAC water ("reconstitution solution") sold on Amazon is something someone cooked up in their kitchen with tap water - possibly in-between cooking up batches of meth.
- Never buy BAC water (or any injectable) on Amazon.
With genuine Pfizer/Hospira BAC currently in limited supply and the price inflating rapidly, along with the ability to acquire it without a prescription becoming increasingly uncertain, it's seeming more likely we may have to start relying on BAC water from China. That being said, just like buying peptides it's going to require more diligence with regard to testing and holding vendors accountable to verify proper pH, BA content, and lack of contaminants.
Almost all the Chinese BAC water tests I've seen are generally close on BA content and free of contaminants; the main issue has been pH outside the desirable neutral range. Fortunately we can easily test for pH ourselves with quality aquarium test strips or an inexpensive meter (which you can buy on Amazon lol). And while there are certain peptides that aren't terribly pH-sensitive, some people may experience ISR's or other discomfort if the pH is outside the neutral zone (and there aren't any Klingons to worry about). Then there are the peptides that are very sensitive to pH, some of which don't even behave well with Hospira BAC and require a much more specific pH outside of the neutral range.
Just like the majority of the Chinese figured out how to produce far more consistent peptides and become more accurate with fills etc. I suspect that as demand for their BAC water increases we'll likely see steady improvement in the overall quality. And with crowdfunded testing becoming a regular practice we will probably know pretty quickly which vendors BAC can be trusted. All of which is still far better than buying it from Amazon.