First you can just open the Style manager and create a new representation marker and create it's graphic from scratch.
Second, using font-based marker symbols, symbolize your layer (or any geodatabase-based point layer for that matter) with the symbols you will need, and then create representations for that layer. Each of the representation symbols can be edited and most importantly saved to a style from the layer properties symbology tab. It's a little tedious, but far better than creating the artwork from scratch. In the Mapping Center blog entry I recently did on
symbolizing one-way streets, Step 4 has a download for a style of arrowheads that I created in this fashion; it took about 20 minutes to do that.