Semper Fi Marine! 101ABD here...
I started with V2 ultimate kit (over priced, but got me off real smokes and has a lifetime warranty - donated to the Mrs as she doesn't like the bigger stuff I use now). Grew into "fat bats" with the LeCig PigCig (1300mAh, last more than a day for me and used the same KR808D-1 cartomizers as the V2) and recently graduated to the LeCig VV (vari-volt Lavatube look alike) and love it with the Vision Stardust. I Still use the PigCigs with IkenVape 901/1.8LR atty for dripping. Biggest cost savings for me was stopping the pre-filled cartomizers. Best middle ground for me would be a fatbat setup (doesn't look like a real cig, but still small enough to stealth). And at 3.4v (for eGos)/3.7v (for PigCigs) with larger capacity (>1000mAh) let's you last a long time (and safely use low resistance stuff later when you start experimenting).