Here are my two favorites:
For under 50 bucks...the
Boge Revolution V2.1 (with 1400mah batteries).
It has a bottom feeding bottle. It's designed to work with Boge 510 vertical coil cartomizers and comes with 5 of them at standard resistance. Also included is a wall based charger. To me, the LR Boge Cartos do work a little better with it than the included standard resistance ones. I have screwed on a 2 Ohm
dual coil carto, and it fires up fine, but not quite hot enough for me. I've not yet tried a 1.5 Ohm dualie on it yet, but folks on YouTube say it works just fine and would definitely vape a bit warmer than the 2 Ohm one I tried.
Here lately, I add a tube from an old windex bottle to the bottle and use regular atomizers (either a 2 Ohm Ikenvape Cannon, or a typical
LR 801 atty with an
adapter) instead of the cartos, but that's just me. I've also used the
cisco 1.7 Ohm LR atties and they do nicely too. The main reason I prefer the 801 with an adapter is because it lightens up the draw considerably, and still feeds quite well. Every few hits, I give the bottle a few squeezes with my thumb and cold-draw to pull liquid into the atty...then I'm good to go for 8 to 12 hits or more. Sometimes it even auto feeds for me once I get it primed and going.
When I want to vape a different flavor that isn't loaded in the bottle, I just screw on my favorite loaded cartomizer, or drip into the atty.
These things are very light and fit the hand and pocket well. They have two long lasting li-poly batteries in them that easily go all day. No extra charger is needed, just plug the thing into the included charger, or use a mini USB cord to charge it on a computer. It can be vaped while it charges.
Even if I never used the bottom feeder, I'd find the little V2 worth the $50 I paid for it. It's not the best bottom feeder out there, but it is one of the least expensive for something that comes loaded with great batteries, a charger, and can be vaped all day. If you buy any other box mod that bottom feeds, you'll get close to this price and still not have batteries and a charger to go in them!
Here's a V2 Review:
http://www.youtube.com/watch?v=b81qEbS5nsY
Note: The V2.1 still has the alien lights on top, but no anion thing in the unit, instead it has an extra battery bringing it up to 1400mah.
Of course I love my
Darwin. All the other stuff...Boge V2, eGo, etc...now sits on the 'back up shelf'. Or I occasionally pull the other stuff out for parties or travel where I fear the Darwin might get lost or stolen. The Darwin is awesome, can run pretty much any carto or atty on the market at very high performance levels, is built like a tank, and is very easy to use. Like the Boge V2, Darwin has built in Li-Poly batteries...so I don't have to mess with chargers and stuff, and no daily fiddling with changing the batteries.
At first I was skeptical of mods that use Li-Poly batteries instead of Li-Ion. So many folks swore they'd never own something they couldn't easily swap the batteries every day, and even more swore they'd never touch anything but 'all mechanical' devices. I finally gave in and tried these two devices. Now I'm a believer! They are far lighter than a comparable Li-Ion battery. They are rated to last at least twice as long (recharge cycles...typically up to 3,000, where regular Li-Ions are usually rated at more like 400). And best of all, I don't have to swap them out all the time. Just top them like a cell phone at bed time every night or two and run with it

Neither of these devices have given me a lick of trouble over months of constant use and abuse (even including days of floating around on salt water in boats).