I have developed and restructured pricing models across multiple organizations over the years and one thing has always been true, when it comes to pricing one size does not fit all. There are many models that can be deployed based on a variety of factors including; the scope of the services being provided, duration, resource requirements, business impact etc.. At a minimum, I suggest you start with capturing the scope of services, and clarifying the duration of the project (i.e. is this a 1-month commitment or a 12+ month commitment etc..) also if I understood the question this will require (2) resources? Will need the daily, weekly, and monthly costs (loaded) for those resources? Will they be fully dedicated to this client/project? If yes, is this for the duration/all phases or only certain aspects/phases of the project? Once you have this information you can assess the investment your firm will be making in delivering the work and from there be in a better position to value that in terms of retainers and fee structures. If you would like help please feel free to schedule a call and I will help you flesh this out and create a pricing model that you can apply for not only this client but your future clients as well.