Amazon has the 2-Pack Irwin Tools Strait-Line Lumber Crayons (Black; 666042) for $1.29 with free shipping on $25+ or with Prime (extra 5% off with 5+ items S&S order). 

For use on oily, slick, wet, cold, or dry surfaces. Used for marking lumber, concrete, ceramics, rubber, metal, paper, and cardboard.