Second, the quality of the components make it more expensive to build. I think that you can't compare the MFLB with a FF price wise.
You really can't compare the Firefly to the MFLB. I fully admit that I'm a newbie with the LB, so my technique is far from perfect, but I can definitely produce visible vapor and get medicated from it. That said, the Firefly produces way more vapor, and thicker vapor, and compared to the LB, there is little to no learning curve.
I actually took both my LB and my Firefly out about an hour ago while my wife and I ran a couple of errands. I love the LB...it's small and stealthy and aesthetically appealing. But I have to think about my session quite a bit, much more so than with the Firefly. The LB can and will get the job done, but not nearly as easily, consistently, and thoroughly as the FF.
I'm a pretty experienced vaporist and have converted enough people to vaping and have seen enough people vape to say, with confidence, that I completely understand why the MFLB is such a love-it-or-hate-it vape, even among those who enjoy more manual vapes. On the other hand, I have a hard time imagining anyone not loving the FF (as long as you enjoy this style of vaping).
It must also be said that if you hold the two units in your hands, you will completely understand why the FF costs $150 more than the MFLB.
The weight, heft, and build quality of the Firefly simply doesn't come across in photos.