It's not on sale, but this is the cheapest by a decent margin available in Australia (that I found anyway). As a bonus most places don't even have stock, but UBWH has a bunch.
Note it doesn't come with an injector.
They've decided to make customers pay their strangely high surcharges for Visa and Mastercard, but they take bank transactions as payment which worked fine. I think it's because they mostly sell to businesses.