To be honest, I went over to Harbor Freight tools and picked up a 5/16th" round file, cut off the handle, and ground it into a square graver. I then spent a couple hours honing and polishing it. It is about 4.5" long, and I have been using it to engrave ever since. I do have some 'real' gravers too that are mounted in wooden mushroom handles, but that cheap Chinese file graver is the one I use for 90% of my work. Surprisingly, it seems to hold it's edges quite well, and I have yet to have it chip out on me. I am more satisfied with that graver than any other I have, truth be told. Granted, it took some work to fabricate, but it has served me well, and when it is too short to use anymore, I will probably make another just like it.
Matt