Locally
Online unicycle shop and local distributor of Qu-Ax brand unicycles. Prices start from $160 for a 16″ uni and $200 for a standard 20″ uni. Other brands may be available from time to time. If you have something specific, drop them an enquiry.
Shopping for unicycles in the internet:
The Japanese Miyata brand is recommended. Ordering straight from Japan is cheaper and you get to save on the shipping.