This is true of antique stores as well. There may be some variations however. Over the years, button prices tend to go up and down. Prices have traditionally been highest just after a presidential election, when hundreds of new collectors enter the hobby. Prices can drop during an economic downturn, as collectors worry about their own economic future and spend less on their hobby.
Prices also vary by collector interest.
Right now, for example, there is no hotter field in the political hobby than woman suffrage items. For several years now Eugene Debs and Teddy Roosevelt have been two extremely popular candidates. Of course by the year 2004 Hoover and Dukakis may have their day in the sun. One of the flattest collecting areas for many years has been the pre-1896 items, especially ribbons and tokens. Data from Hake's Encyclopedia of Political Buttons updates confirms these trends.