Just got this in an email. Spirit I and Spirit II are celebrating their birthday this September and to celebrate we are offering you special birthday fares!
Pack your party streamers and party hat with Ocean Recliners from $54* per person each way and cabins from $120* per person each way.
This special offer is valid for travel between 12 August - 6 October 2013 and is available to be booked from now until sold out.
Book now and get into the party spirit!
(Similar to deal: http://www.ozbargain.com.au/node/101308 but extended travel dates to 6th October, 2013)
*Conditions apply. Birthday special available from 27 May 2013 until sold out. Offer applies to new bookings on sailings between 12 August – 6 October 2013. Limited availability on selected sailings. Fares are per person each way. $120 fare applies to Twin Inside Cabin (twin share). A $5 booking fee per person each way applies when booking via the Customer Contact Centre and Terminal Service Desk. Red Hot Deal conditions apply, click here for details.
Note that prices mentioned "Seats from $54/Cabins from $120 (twin cabin)" are children prices.
What is more interesting, is that I picked dates outside this sale (for example in November) the the prices are cheaper where childs price is Recliner Seats for $42/Cabins for $108 (twin cabin).