In the states, I went to two OfficeMax stores before finding a HW:B1 one.  One store had only HW:A1.  One store had all HW:A1, except the HW:B1 that I bought.
I think it is a matter of waiting, if you can.  After the HW:A1 units sell-out, they'll back-fill with HW:B1.  I'd venture to say that most people don't read these forums, so the HW:A1 units should sell pretty quick.