From what I would consider medium quality content about 20 bucks if that an article.
With that said to answer your second question pay by word is good for writers you have already dealt with and somewhat trained. For new writers, you have no idea about their skill level you pay by article flat rate. Sometimes it's even best to get a sample of their work in your niche, you don't want to pay 20 bucks for fluff either you know.
On average for medium lvl content-id say 15 - 20 bucks and if it's a little bit better than medium with a writer you work with often maybe push it to 30 bucks again depending on the quality.
So to average it out; a freelance writer would earn about $22.50 for 1500 words, of medium quality content.
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