The publishers that charge advertisers the highest rates are those in the travel, tech and automotive verticals, according to Adify, which buys media on 12,000 publishers for 200 ad networks. Below, see a chart from Adify that shows what rate — CPM, or cost per 1,000 impressions — publishers from 13 different verticals have charged advertisers over the past three quarters. Travel leads with a $19.89 CPM; tech is second at $16.01; food is last at $3.63. Read more at www.businessinsider.com