I am a horrible procrastinator, so commissions would never get done timely. Also, more than one of my novel ideas have sprouted from what was originally meant to be a 2k-5k word short story.
That's how it usually goes. I give a number and don't charge extra when I get over it. Sometimes I give double the word count. But, that's what being a writer is all about. <3
Link
Xinnova
O.o You could always do commissioned stories for people. Works just as good as a book lol.