so im trying to save up can money and do odd jobs, etc. to save up money for a mod bos (i thinkk thats what they are called( the top of the line ones( im only 20 in so far, but i thought about buying used) if i were to buy used what should i look for? im only a week into this vaping thing so im a complete n00b. any suggestions would help. i just want something better than a pen. the pen i got leaks, both at the tube, and back into my mouth (EWWW!)