http://www.dustbooks.com/

Sometimes the best place to start is not sending to the biggest pubisher, but to a small press more open to a variety of writing styles and themes.  I don't mean vanity presses, but  publishers who pay their authors (rather than the reverse).

Dustbooks has a number of directories on small presses and little magazines, that might be interesting to browse through if you are having trouble breaking through the bigger markets.

Can't afford to buy a directory?

That's what libraries are for.