Further to the Rumpole Box Set thought I would post this, is a great price.
The Complete Yes Minister & Yes Prime Minister - Collector's Box Set [DVD] £12.24 post £3.68 Total £15.92 AUD$25.29 from Amazon UK, region 2 DVDs.
It shows price as £14.38, but when I purchased it, the actual prices were reduced.
Please note that Australia is Region 4, so to play these discs you will need a region-unlocked (or "region-free") DVD player of some kind.