In this area, at least, early blight appears in the gardens of almost everyone who grows tomatoes. Perhaps some people who are fanatical about spraying don't have it but, otherwise, it is ubiquitous and usually not that big of a deal.
Personally, I've weighed the idea of eating tomatoes that have been sprayed with a fungicide versus losing some production to blight and chosen the latter. But, we get more tomatoes than we can eat every year so loss of some production doesn't hurt much at all.
The only real effort I make to avoid blight is to simply quit growing varieties that showed the most susceptibility to it in the past.
People who use fungicides have a number of options. Daconil, Maneb, and copper-based fungicides seem to be the most commonly used ones around here.
Here is a link with some good information:
http://extension.umaine.edu/ip...