This niche is saturated, its very difficult to enter into and sustain there.But still people found potential to invest money and time into it. Most of peoples are followers and they don't try new thing and because of it they never test the real success.
If you can find relevant keywords with not too much competition for article directories, then why not?
There are tons of keywords out there man, its just a matter of testing them all to find which ones are worth your time and/or money... Good luck!
I make 95% of my e4e sales from articles, so I would say it is very doable. Just shoot for long tails.
I have about 40-45 e4e articles, so really its not that many. At 250 words you should be able to crank them out in 2-3 minutes a piece.
How many sells per week are you averaging? I guess you used google keyword tool and wrote on 45 different keywords? I am just getting into this myself.