whats the best portable fog machine for photoshoots?

So i am thinking about possibly adding some fog / smoke to some of my shoots, i know sometimes it looks cheesy but sometimes it can add a cool element if done right... SOO my question is whats the best (less expensive of course ) portable fog machine to bring out in location shoots? water based fog of course oil based would screw up the gear.

Thanks
Jacob

I think B&H sells fog machines,might try them. I know nothing about them