There are a few places to get ukes around here, althought the selection isn't usually all that great.
Try Milano's Music in Mesa, or maybe Bizarre Guitar in Downtown Phoenix. Of course, there's a few Guitar Centers around but they don't usually have much. There's also Central Music that might have a few, and I heard Music Brokers in Phoenix was going to start carrying Kalas, but I haven't been there for a while.
I also noticed that there are currently a couple people selling inexpensive ukes on Craigslist in the Phoenix area.