With research, I charge ten cents a word for the set word count, whether I go over or not (a.k.a. if you contract me for a 350 word article and it ends up being 400 words, it's still $35, as I don't write to specific word count, just the general vicinity).
A Look Back: 1981
(more on that website at An Instant In Time Articles )
My blog: Joe Camper
You can find some of my shorter work at Zhorkow's CargoShip at StarHatch.com in the library and reviews sections (the Dungeons & Dragons article is not mine).