From the information I read it looked as though there are 2 main options a 510 or an eGo and I would be looking for the best place to purchase a starter kit and the nic juice.
Battery Info- 100 mah= 1 hr normal vaping before recharge is needed.
510 is a mini ecig/ cig sized PV- usually about 180- 280 mah
BUT 510 can also mean the threading of a PV and is the most common of threading- 808 is the next type of threading. If buying a 510 threaded PV the accessories must be 510 also.
Cig sized, automatic batteries: Volt, Bloog, Smoov- cig sized and battery life is an issue- 808 threading-somewhat limited with the accessories you can use.
Smokeless Image | Only The Best Electronic Cigarette | Smokeless Image Electronic Cigarettes - The Future is in your hands Starter Kits from $20- $95. Comes in auto and manual. I chose Smokeless Image as they sell quality products, prolly have the best Customer Service within the industry and have a large and loyal following. With 808 the user is limited to the delivery devices (holds and vaporizes the Juice)
eGo Class/ style, manual push button batteries:
JoyTech eGo fires @ 3.3 volts, SmokTech eGo fires @ 3.7 volts and the Riva/ Kgo fires @ 3.7 volts- come in 650, 900 or 1100 mah depending on the manufacturer- most popular 510 threading/ connection and are manual. I own a Kgo and I LOVE it. Have used the JoyTech eGo and prefer the Kgo because of the higher voltage.
eGo Starter Kit cost anywhere from $50- $80.
Riva/ Kgo starter kit costs about $40-$50:
Mini Variable Volt PV: 510 threading/ connection. Manual Push button batteries
Kgo VV- only comes in 650 mah- I own it and find battery life a problem.
Twist comes in 650, 900 and 1000 mah. Dial very narrow/ smooth and not easy to turn. Voltage numbers very hard to read/ invisible. Button occasionally sticks.
Vision Spinner comes in 400, 650, 900, 1100 and 1300 mah. Wide knurled voltage dial easy to turn and easy to read voltage markings. 1300 mah Spinner is the same size as 1000 Twist.
Both variable voltage PVs above fire from 3.3-4.8 volts.
I owned the Twists and now use them as backups because the dial was hard to turn and I could not clearly see the voltage markings.
1300 Vision Spinner- 113mm or ~4.4 inches long; 16MM WIDE, 2MM WIDER THAN A STANDARD EGO
1100 Vision Spinner- 119mm or ~4.75 inches long
1000 Twist- Length 120mm(4.75")/Diameter 14mm
Advantage of the VV- when stressed and need a stronger hit I can easily and quickly dial up the voltage.
I would prolly recommend either the 3.3 volt JoyTech eGo or the 3.7 volt Riva. They are 1000 mah batteries.