Setting a price is one of the trickiest part of freelancing.
In the freelance world, it can be a bit complex when it comes to deciding what you should pay for copywriting services since ever project is unique. You can set a price per word price or a price per page or document price but ultimately you should always examine a job to see if it has any hidden time consuming aspects that could possibly put you in the poorhouse. For instance it is not quite same charging for a 500 word article about baby booties as it for a 500 word article about fractional jet aviation.
via What Should You Charge for Copywriting Services? | Freelance Apple.