Below are my recommendations for where to buy clear ice and have it delivered.
California
LA based and deliver all over California. High quality and made with precision. My favorite cube was the Normandy but they have loads of options.
While living in San Diego I would regularly make a bi-weekly stop at Collins and Coupe to visit with the wonderful team and pickup supplies. They carry several options of ice from different suppliers.
New York
I've not personally ordered from Hundred Weight but a few friends in New York have and they have nothing but great things to say. They also apparently are a large supplier to bars in NYC which says a lot!