I am trying to get some $ figures, either as an average of the
fast-food industry as a whole; or from one or two chains that are
large enough to be representative of the entire industry.

For a fast-food chain:
----------------------
- The $ cost to acquire a customer 
- The $ cost of losing a customer
- The $ lifetime value of a customer

Obviously the $ values will change from country to country so the
answer should explain if the values are for a specific, named country;
or for named supra-national region.