Dear
Our firm manufactures     [type of products]
We are interested in investigating the possibility of
national advertising.
We would be very appreciative if you would provide us
with your rates and any demographic information you may
have on potential users for our products which we feel
primarily fall into the following category:
                [sex and marital status]
                       [age range]
                 [other characteristics]
Thank you for your prompt attention to our request. We
will be looking forward to hearing from you.