Mrcool - there is no "standard" price or fee as this would clearly be an anti-trust violation. Yes it is perfectly legal for the brokerage to charge this additional fee, and as Hiedi indicated most companies will accept the fee from either the customer or agent.
OUR firm DOES NOT charge these fees - we quote the commission and that's what you pay - agents working with buyers are paid from the sellers listing commission.
The problem I have with the fee these companies charge - is the disclosure - when does the customer find out they are paying it, and I believe some (not all) use "fine print" to hide these costs.
Unfortunately as more and more of the commissions go to the agents (not the brokerages) then many are left with little choice but to find additional revenues. Maybe not right... but true.... more