You might want to look at a Deep Blue Professional tank. Here is their product catalog:
http://www.deepblueprofessional.com/web%20catalog/dbwebcat.pdf">http://www.deepblueprofessional.com/web%20catalog/dbwebcat.pdf</a>
Look on the fifth page down that says "Frag Tanks." I own two of their rimless 34 gallon Reef Ready tanks, 24" x 24" x 12". Don't know if 12" deep is shallow enough for you, but I bought mine at Aviarium. I think Imagine Ocean, Pure Reef and SEA stock them as well, but any Sponsor should be able to order in your choice. There are other Deep Blue Professional shallow tank sizes as well, just look at the catalog.