Management consulting firms have a wide range of billing rates depending on the level of staff, e.g. consultant vs. manager vs. partner. They charge an hourly rate and number of hours can be anywhere between 8 to 40 hours per week. The expenses are usually separate and can be as high as 20% of professional fees. The clients have gotten smarter about fees over time and many of them request the expenses to be reconciled to actual expenses at the end of the project.
Below is a graph that should give you a rough idea of the hourly billings rate for management consultants by level. There is a spread for each level, the top firms typically charge at the high end of the range. These are rates for strategy consulting staff, there are specialized experts (e.g. IT) that could have a separate rate structure and are usually cheaper than the strategy rates.
As you can see, the rates are range from $250 all the way to $1,200 per hour, so it very much depends on level of staff, the level of discounting in the deal, etc. to get an average blended hourly rate.
The firms do discounts of up to 20-30% but it is usually reserved for high-volume clients, for new logos. If the business is soft in general, they are more willing to negotiate.
Keep in mind that these are the rates that the management consultancy gets from clients, not how much they pay their own staff.
Please let us know what you think and share if you have any other data points. Thanks!