Cable cheaper, yes. Cable works at home, yes, when you have power.
Brick more expensive, yes. Brick works at home, even when you don't have power.
That's why I got one. The traveling aspect is just a bonus.
We lose power at our house on a regular basis, at least twice a year. So I use the brick to charge my flip phone every week. After a month or so, I charge the brick to keep it near a full charge because I can't charge the brick when the power is out. The mfr. recommends not just letting it sit for weeks on end, so that's the approach I take to make sure it stays in good working condition.
