How long is too short?

Well, YA novel wise. After a grreat deal of trawling through publishers websites, the ones which care to give details of requirements, not just the requirement that they don't require anything at all from you new writer, thank you very much, but actual submission requirements, I have found that word counts can vary between 20,000 and a vague 'around 50,000.
So, at the moment I'm around half way through, meaning I will manage about 30, 000 words, but it seems I will be narrowing down the list of possible places to sub, which is pretty narrow already.
Frown.
Hmmph.
The answer is to just get on with it and worry about where it goes later, I suppose.
Which I should really do, having already accumulated a number of 'nearly finished' novels that have no home to go to :(
Do you write for a target market and therefore a specific word count, or just go with the flow and figure out what to do with your masterpiece afterwards?

Mischa doesn't really care either way.