I get a little giddy thinking about gear shopping, so here's the long version: for white mist and low-lying fog machines filmmakers have a ton of options. First stop for me is always specialty pro-theatre and stage suppliers — brands like Antari, Chauvet, Le Maitre, and Rosco make reliable units and dedicated low-fog systems. Those vendors sell machines tailored for film: quieter pumps, DMX control, and fluids optimized for camera work.
Next, I look at large photo/video retailers like B&H or Adorama, which stock pro and prosumer units and often include specs, customer reviews, and bundle deals for fluids and hoses. If budget is tight, I also check used-equipment sources — eBay, local marketplace listings, and rental houses clearing old kit. Rentals are great if you only need the effect for a day or two and let you test different machines on set. Personally I always match the machine to the shot: hazers and foggers for soft ambiance, low-fog chilled units or glycol-based low-lying systems for that thick white ground mist. Safety matters too — ventilation, correct fluid, and checking for glycol vs. water-based compatibility with actors' makeup and lenses. I usually finish purchases after testing a rental and reading threads from other filmmakers, and I end up happier that way.