Well yes if you can get the right price. eBay sellers tend to gouge prices immensely due to fees and such which makes buying from them even with bitcoin not worth it most of the time. I've found a few deals for slightly older miners but that's about it; of course if you want to avoid import tax you can also buy from such people, albeit at a higher price than from some people on the forum.
This guy is selling each S9 for 1 BTC.
It seems a good deal to me considering I'll pick it up and not paying in advance.
I have no experience with these miners so I'm afraid it might not be at 100%.
I guess it's not the ability to authentify documents, they do great work for authentication (through live person call, dedicated photos to btcjam etc ...), it's more about the ability to track down every one running out with the money, it's not that easy to open cases worldwide ... there's different laws, different systems, and one more thing: bitcoin is forbidden in many countries in the world, so how will them pursue someone through his local laws ?
Force worldwide cases.
The problem is that they can't even collect in the US and first world countries.