Proper haze machines (machines which use a compressor or compressed gas) produce a particle size much smaller than a generic smoke machine. This smaller particle size means that much less fluid is used and the effect hangs longer in the air as smaller particles fall much more slowly than larger particles.
Widely regarded by many in professional production fields as the best haze machine available due to its very small particle size. Not cheap though unfortunately, at GBP 1460.00 +VAT for the basic PS48 model (March 2014), GBP 1595.00+VAT for the PS49 model with fan.
Widely used professional cracked oil machine.
American DJ Haze Generator / Antari HZ-100/ MBT HZ100
All the same model with different branding. Low cost equivalent to the DF-50 according to many users. Good for smaller venues. Apparently works fine with oil produced for the DF-50.