Just stay away from those "hustlers" that will tell you that Japanese tubes are better than Telefunken or Amperex!
I also had the experience of buying 12au7 tubes from a local seller that went bust after 3 months, and I bought it from a reputedly "honest" seller from another local forum!
Not only 12au7 tubes, I got some 6x5 tubes from a local seller that gave my preamp oscillations which took me a couple of months to isolate.
![Angry >:(](https://www.pinoydvd.com/Smileys/default/angry.gif)
He also sold me some Siemens caps that leaks oil, upon checking, those old Siemens have PCB in them.
![Shocked :o](https://www.pinoydvd.com/Smileys/default/shocked.gif)
Latak na yata ang binebenta nito.
The best insurance is to have the tubes tested before handing over your hard earned cash. In fairness, there are a lot of honest sellers. Get from those who are willing to give you warranty.