You can try
http://www.dddsportswear.com
You can also just go to yahoo.com and just do a search for "referee apparel" and you'll get an enormous amount of hits.
However - Honigs is the best.
Question - does your league not provide you the official's jersey/whistle/lanyard? Mine does, but I bought my own. They use that dreaded collared shirt, a pea whistle, and an 'around the neck' lanyard. I got a V-neck, FOX40 whistle, and a 9" smitty lanyard.