Here is my logo for your consideration. I incorporated a graph with a rising arrow, which signifies the savings of a 401k plan. Let me know if you would like to see any variations, and I will be happy to provide. I used green, per your request, and I think it's a great idea to do so, as people directly connect it with money and financing. I also kept the logo as a one-color logo, so that it can be easily recreated on anything (from printing to embroidery to engraving).