Badly constructed CO2 Regulators?

I would like to know if anyone has had experience with poorly made CO2 regulators. I bought a no-brand regulator at my local shop 9 months ago (July 2012) and yesterday morning when I was kegging a new batch I noticed that the regulator out pressure just kept climbing. Even when I turned the regulator dial all the way down the pressure would continue to climb with no indication of stopping. It is lucky think that it happened while I was looking at the dial when starting a new batch because otherwise the keg would have gone to who knows what pressure and hopefully the release valve on the keg would work, or it would have been one heck of an explosion. Yesterday afternoon I took it back and they sold me another of the same for half price ($40), but when I got it home I found that it does not work at all. I can't get any pressure on the out line at all, plus the pressure release valve is totally non-functional. In other words it is pretty much a piece of .... Obviously I will return it today.

So I have lots of question for people who have experience. First of all, I don't want to be too critical, but isn't it really unsafe to be selling this kind of equipment? I mean, I am batting zero out of two on this equipment. Secondly, I talked to a major supplier this morning from whom I am buying a supposedly better quality piece of equipment. Do you think that I can trust it? And thirdly, I just want to know what other experiences people have had with this problem.

I blew a plexiglass tank under 5 psi in a lab once, and it is heck of a blast, with holes in the wall and all. I can't even imagine what a 50 psi metal tank explosion would do. The point is that pressure is dangerous. Getting into the kegging I was under the assumption that safe equipment would be sold. I am not so sure anymore. Just a word of caution.