Buy local. HP has a dealer finder on their web site. When you buy local, you're helping to support the people and businesses in your area whose livelihood depends on selling these products. Part of the money you spend on this one product then goes back into the local economy in the form of rent, groceries, etc.
I don't know if the prices on the Z series have softened any, but when I bought my 3100 there wasn't much difference between the online merchants and the brick-and-mortar ones, making it even easier.