Chris Sherman, Offshore Division, HSE writes an intersting article SCUBA Diving with an Octupus.  What Chris is really talking about is the extra 2nd stage most divers have attached to their regulator.  I will soon be purchasing a new regulator (I can no longer get parts to service my Dacor 960, thanks Mares), and I am considering which Octupus to add. 

The extra Octupus can range in price from about $60 to over $200.  Also you can now have the Octupus intergrated into your BCD.    When considering a new Octupus the main thing to keep in mind is that THIS MAY BECOME YOUR PRIMARY REGULATOR if someone your are diving with runs out of air.  Pick a Ocutpus you trust.