Usually my posts are in the range of 140 to 350 words. It varies wildly because I keep each post very unique. One post for your product might be heavily review driven with specs, samples, etc. The next post might be reflective of something the product reminded me of with a plug for the product at the end.
Often my customers will come to me telling me that my style is like night and day compared to what they were getting. I always try to make my posts worth reading. I don't write for the bots. I write for my readers. My blogs are not filled with mindless posts you normally see when somebody sells posts.
I also write many posts on my blogs that don't sell or plug anything.
Many of my customers buy 50 to 100 in bulk for the bulk deals and then use them over the course of 2 or 3 months as they come up with new projects.
Come check out the difference. I will extend the Cyber Deal all the way until Friday night!