I would agree that trying a dab of fluorescent nail polish on the front site would be an inexpensive first try for your EC9s. I applied a couple coats of traffic cone orange nail polish from wallyworld on the front site of my LCR and it is a big improvement, maybe not optimal, but works for me. Another option you might consider would be to install a laser sight. Even that should be cheaper than custom milling the slide to replace the current front site, which after completed might not turn out as good as one might hope.