expired Lego Duplo Basic Bricks Deluxe Set $24.95 from Mr Toys Toyworld (QLD)
I noticed on page 5 in the Mr Toys Toyworld Catalogue they have Lego Duplo Basic Bricks Deluxe (6176) for $24.95
This is the cheapest I have seen this set of blocks - 80 pieces - last time Toyworld had it in their Catalogue it was a couple of years ago, and was close to $40. They say it's an exclusive to Toyworld, but there are couple of other places you can buy it from online, the next cheapest is $32.99. This set doesn't have any fancy pieces, but is a great way to build up an existing set with extra blocks, and I haven't calculated all the sets available, but I think would work out to be among the cheapest per block available currently.
Various stores located across Brisbane, Sunshine Coast and Gold Coast