Ma Dalton just let me add my two cents worth to what the others have already said.
1. Never buy story content based on price alone. If your only prepared to pay peanuts then the only people who will read the story are monkeys. If you want good written work then you need to be prepared to pay for it.
At the same time the normal market forces apply here just as they do anywhere else and you can get a good story for a very reasonable price. If a writer advertises a price on their website don't always take that price as being set in concrete.
2. It's far better not to use stories at all than to use poorly written stories just because they're cheap.
3. Most of the people who claim to be writers aren't. Writing a good erotic story that will capture the interest of your readers is about more than just two people copulating.
4. Most of the people who claim to be writers aren't. There are special techniques that should be used when writing a story for the Internet and most people don't understand that or can't adjust the way they write to accommodate those techniques. Long paragraphs are just one of the BIG no-no's when writing for the Internet.
Oh and did I say that most people who claim to be writers aren't?