Style guides may range in length from a few pages containing the bare essentials to hundreds of pages including hundreds of pages of detailed information—as previously said, the cost of a style guide can vary substantially. It's reasonable to expect to spend anywhere from $3,000 to $10,000 on a competent style guide. In the end, the cost of developing a style guide will be determined by who you engage and how large the scope of the task is. Just like with logo design, graphic design in general, or any other creative service, the cost is determined by who you choose, their experience and skill, their location, and other factors. Despite the fact that everyone can design a logo, I do not think that any designer can create an excellent standards document. Building a style guide is a time-consuming, frequently difficult task that only experienced designers would be able to do successfully.