We have several key customers that are pushing many QS requirements down their supply chain (APQP, PPAP, etc)without requiring us to register to the QS standard. I am trying to present to Mgt. a cost breakdown so that I can estimate the cost to our organization for preparing and allocating the appropriate resources for APQP and what costs go into each APQP or PPAP process (i.e. cost per new part). If anyone has any thoughts or guidance on how to best breakdown or explain what these costs may be, I would greatly appreciate it.

This is very dificult to breakdown without knowing your product.
If your parts are similar there is a possibility of a generic approach.
The main reason behind the APQP system is to save you money and ensure the customer the correct part.
The system might in the short term cost money but this should repay itself with reduction of entry time and scrap at project start as well as improving customer satisfaction.

Most companies, and yours is probably no exception, already do everything that is normally required in APQP. What they don't do is document what thay are doing.
For starters, figure the time it takes to fill out all of the forms and multiply it by the company's hourly rate. Should give you a ballpark figure.