I bought my ZI, in black, from Photovillage in NYC (they also advertise here). I live nearby and wanted to handle the camera before buying it. Rich Pinto, the owner, is pretty knowledgeable and easy to deal with.
The one serious drawback to Photovillage, however, is that there are *so* many goodies on display that I always end up giving in to temptation and buying something more than I intended. Beware!
I've purchased items through Popflash and would also recommend them highly. Very good prices and attentive service.