There are two high end convection brands I know of, the Volcano (500), and the Vapir, which I'm getting soon. These run anywhere from 150-300 depending on what model and if you want a cordless recharable or not. The low end Vapir actually supports bag filling, which is nice because you can fill it up and pass it around.

The very important thing to remember is you're going to be getting about 90% of the THC out of the herb, compared to about 20% if you smoke it. You need a lot less. I've seen too many people pack a gram and make themselves sick.