They want one hundred 500-word articles/blog posts written with SEO in mind for $100-200? If I had breasts and a vagina, I could make that much by letting someone take pictures of me for half an hour.
Honestly, if someone had it in them to create that much text content, it would be far more profitable to use it on their own blog(s) than selling it for $150 while having every article scrutinized by the buyers.