If you do any amount of mailing, and use stamps, you may want to stock up on those forever stamps soon. Eff. January 27, 2019, the cost of mailing will increase.
I know many REALTORS have stopped doing direct mail, and the very reason I continue to do so. Many times I send out postcards for Just Listed or Just Sold, and only see my postcards when they call for an interview. I bought a few rolls of 1st class stamps and a roll of postcard stamps.