Hello,
My sorority is in the process of re-doing our coat-of-arms. We are working with a company called DKS Designs (their website is
http://www.dksdesigns.net ). I tried to work with Fleur-de-lis for months but there response time, even on simple questions, is horrendous. Plus they never answer their phone. Anyway, DKS Designs specializes in the design of coats-of-arms and their designs are totally in line with traditional heraldry rules.
I've noticed that a lot of new Greek organizations have moved away from the traditional-looking coats of arms and have come up with more creative designs. Although DKS advertises they do that, I would think if you had that sort of thing in mind, you could just go with any graphic designer or artist. The resulting design can be registered as a corporate trademark, but not as an actual coat of arms with the American College of Heraldry (note: registering is different than granting; that can only be done by a monarchy-type government...and we don't have that in America). This decision can only be made by your group; but it makes sense that the coat-of-arms for your group be an actual coat-of-arms and not just some picture...but that's just my opinion.
Just about all of the NIC/NPC fraternities and sororities have genuine coats of arms.