Are you sure it's still cheaper to roast your own, if you look into the energy bills? (Not to think of your own unpaid work.)

If you calculate your time, almost certainly no, at least for pan roasting.

Yes. Though the energy is probably not that expensive for you as I thought initially.

use a $9 popcorn machine. it's easier and much much faster (takes me 5 minutes).

it does generate lots of smoke, so be sure to do it outside.

It's certainly cheaper than an official bean roaster. I'll have to buy one and see what a popcorn machine is, because I don't think I've ever seen one, and I assume you aren't talking about the ones at movie theaters.

I presume the GP is talking about air poppers: http://en.wikipedia.org/wiki/Air_popper Basically, they funnel heated air into a small chamber.

My girlfriend's dad uses his to roast coffee and swears by it. I don't drink coffee myself (can't stand the smell) so I can't give an opinion.