They have large staffs that usually represent a broad spectrum of technical understanding and experience. Partly because of their size, they tend to operate in a more highly structured and formal manner than smaller firms and tend to be relatively expensive. Many of the small firms are more specialized. Their approach can be more easily tailored to the needs of an individual institution. These firms are frequently less expensive.
Cost is an equally poor means of choosing a consultant.
The least expensive consultant may, in retrospect, turn out to be so inept as to be very costly. On the other hand, the most expensive is not necessarily the best either. While this may seem high, it must be kept in mind that consultants pay office rent and require administrative support personnel just as any other professional. In addition, they must spend a large amount of time just keeping up with the industry, and this is time for which they are not compensated. Most consultants will quote a fixed price, or a range with a minimum and maximum, for performing a specific task, usually with a stated rate per day for extras outside the agreed scope of work.