Their 50% off deal became quite popular in August. Now they seem to have increased the discount further to 55% (plus free shipping). I am not sure when the offer expires but this is definitely a great price for anyone looking for a decent mattress in a low-mid price range. There are a few options to choose from.
The shipping time is around 7-8 days. You can see more comments about the same under the previous post above.
Some of these mattresses are available on Amazon as well - there are limited reviews on Amazon AU but the US listings have more reviews if you would like to check.