Shee, I've been fighting blight this year also, first on potatoes, now on tomatoes and peppers. I bought the Daconil liquid spayer mix and sprayed very thouroughly. It took me two evenings to spray 95 plants, and I probably used 5-6 sprayer fulls. I covered the leaves until there was a little of the whitish substance left on them. So far after one time spraying, it seems to have stopped it for the most part. The peppers made a total turnaround after one application. That was a week ago, and we've had rain every day for the last two-three days so I will re-apply the Daconil this weekend. That's the darndest part of it all, last year I couldn't get enough water on the garden, this year it's too much! Sure would be nice to have a normal year every now and then!
You might need to buy a new sprayer, I just used a gallon size plastic cheapie one from Wal-mart. I wasn't sure what I had put in the one I had, so I didn't take a chance.
So, I think I saved the plants, but now I think I will have to fence the garden to keep the chickens from eating the 'maters! Good luck!