It depends on how comfortable you are with discussing the financial aspects of the treatment.
If you are comfortable, then do so, but bear in mind that patients will often not take in most of what you say on the cost, especially if they have just received some challenging news about their problem.
If you are not comfortable, as is the case for most Consultants, or if is not appropriate, then you will need to set up a separate process to cover that discussion away from your clinic.
This can be achieved by a call from you, your secretary (if they are happy to discuss finances), or a billing agent.