yah, i got mine for $39. for $39 it's awesome. mine is the "authentic" 150w TC model. it's the same manufacturer, but i think Praxis bailed on the deal because it wasn't a very successful mod, so the manufacturer added TC, fixed button rattle and released a v"1.2" without Praxis. the TC works so-so. i don't think there's a way to lock the resistance. at least i haven't been able to figure it out.
other than that, it's been great as a straight wattage device. it takes a little longer to ramp up at higher wattages. not sure if it's underpowered or it has to do with the pulse width modulation (this is my first PWM device). but for $39 it's a good deal. it looks great, feels awesome in the hand, lightweight (yet still solid feeling), and seems well built. everything fits together nicely with no gaps or funny rattles.
sad part is i'm probably going to sell it. i've only had it for a week, but i pre-ordered the Sigelei 213w the other day and it should be in by month's end. i'm sure that will take over as my dual 18650 device of choice.