There is no such thing as a uniform pricing.
While there may be an average per page price among some companies and freelancers, the pricing is set by the respective company or writer. Sure, some companies may adjust pricing to be more competitive, but for the most part, it will depend on the company/writer you select and the work involved in your project.
When I price projects, I look at more than just the number of pages needed. I look at the information available, the complexity of the project, and other factors. Certainly, the scum companies play around with low pricing and higher pricing to give customers a feeling of "getting a good deal" or "if it costs more, it but be better quality." It really depends on the company, their quality, and their customer service as to whether the price they are asking is worth it.
Personally, I provide the best quality I can whether I'm working on an easy (average priced) or hard project (priced slightly higher). But these are just my preferences and policies... other writers will differ.