I found this thread because I wanted to say that I just picked one of these up for $20... and at $20, it's pretty awesome. I had the chance to hold it in person etc, so I understood the build quality in advance. If it breaks, I figure I can fix it... if the housing breaks too much, I'll reuse the circuit. For the money though, pretty hard to beat.
My only complaint so far is that it seems to run for about 1 second after you let up off the button, which is fine once you realize after that first draw off of it.
I didn't get instructions with it, so it took about 90 seconds to figure out... which is more than I can saw for the MVP2.
The gripper I bought came with a little 510 to CE4/5/ego+510 adapter on top... I'm thinking that adapter is worth a couple bucks on it's own as I do still have a few of those CE4/5 tanks around.
I'm thinking that for the $20... it's worthwhile just for the resistance and battery meter function...