We thought about doing this with our directory last year to try and pay for it, but we just ran out of time and energy when trying to put it together.
Calculate your advertising cost based on your production cost plus any extra money you want out of the project:
Our directory was about 24 pages, and we had about 350 or 400 copies made (one for each family). We had it copied at the local UPS store for about $1.50 each.
At $550 or so in costs, we determined that we could sell the back cover inside and out for $20 for 1/16th of a page and pay for the project without increasing production costs. That's pretty inexpensive for a year-long sustained ad.