I second the Vtube suggestion. Use code Vtube30 at apolloecigs.com and you can get a mini or full sized Vtube kit, including battery and charger for $50 in Aluminum, $60 in Chrome, and $73 in stainless steel. Shipping is free and there is a one year warranty included. Another code you can use for an extra battery is "fireworks" for 20% off through 7/4.
Unlike the disposable eGo units, the Vtubes use replaceable
batteries. The one year warranty means that when an eGo is headed for the trash can, the Vtube will still be under warranty. When the battery inevitably wears out, you won't throw the whole e-cig away, you simply buy a new battery for $8. When the performance of the battery starts to decline and it doesn't hold its charge like it did when it was new, you can buy a new battery and restore the brand new performance without having to decide whether to replace your eGo or just live with the decreased performance.
By the time you buy 2 disposable Twists, you'll have spent about the same amount of money as you would if you had bought a Vtube and two batteries. Furthermore, the larger battery capacity means less frequent recharging and that means a proportional increase in overall lifespan.
If a fixed voltage is satisfactory, the kGo is a good mid-sized unit with more power than the eGo systems.
If you want the additional power of a variable voltage e-cig, the Vtube is a no brainer, especially with the 30% off discount and when compared dollar-for-dollar to the disposable Twist.