The key, in my opinion, as to whether an APV or "mod" is worth it from a cost perspective is pay attention to your battery expense.
I was using Twists and they're fine but are "sealed units". When the battery goes (and it will, nature of the beast, they don't last forever), you buy a new Twist.
Best price I was getting was in the $25 to $30 range for 1100mAh. But 18650 batteries of twice that charge capacity run around half or less that price ($10 to $15).
My VTR will "pay for itself" in, oh, a year... ish? I'm hard on batteries. My Twists would decline (work but not hold a charge as long) in six to nine months. So... two, oh, say, $12 18650s per year verses two $28 Twists is $24 verses $56. Less than half. And that's assuming equal lifespans. Which may not be fair as we're actually talking charge cycles and a 2200mAh is charged half as frequently as an 1100mAh if used at the same rate (more or less).
Cheap upfront can sometimes mask expensive over the long haul...
