Vaporizer questions

What up everyone, well i was thinking of buying a vaporizer and i have a couple questions;

1. Does it smell?

2. Is it loud?

3. Is it efficent?

4. What one would you recomend?

My price range is no more than 300$ and i would like a cordless/portable one if possible but please tell me about the ones you would recomend. Thank you.

no, no, yes, ive heard someone really recommending the blue meanie or something. i cant really answer the last question.

What is a humidifing (sp?) disk and how long does it last and how much does it cost?