Sometimes it's impossible to reach all the houses in the area your pet went missing. One option is to use USPS Every Door Direct Mail to help reach more homes. At the time of this entry, the cost of mailing is as low as 18.5 per mailpiece.
According to USPS, there are 3 ways to use "Every Door Direct Mail"
From their site:
1) You Prepare The Mail You can print the postcards with us and we will send them to you for you to complete the preparations for the Every Door Direct Mail program. We will assist you in creating your paperwork and consult with you on preparing your cards for Every Door Direct Mail delivery.
2) We Prepare the Mail For You For only 3 cents more, we can prepare all of your paperwork for you and bundle the mailing exact to post office guidelines. Once prepared, we ship the cards to you and all you have to do is drop them off at the post office. We do every thing for you except drop the cards off to the post office. Every Door Direct Mail that really is turnkey!
3) We Handle It All We can ship the cards directly to the post office at your request.
*** Please check guidelines for printing and mailing cost before starting.