The catch here is that I'm not even allowed to inspect the machines.

I spotted there's a little bit cracks on the case when I bought mine so I want to pick another one. The guy says

"Bro, it's dirt cheap and we will trash them if no one buys them. Don't be so picky"

I was only allowed to power on and make sure it's functional. So buying the rest might be a bet unless they let me check the labels... Or I buy them all. LOL