I would agree with ProfCrash but then I am biased in favour of the Kindle
Borders stock the Sony and usually the Kobo - the Kobo seems to be out of stock at the moment though. There is also
Sony itself. The price seems to be the same.
Another source could be
JB HiFi. I don't know what their readers are like though.
There is also the
Kogan. I have read both good and bad things about it.