If you check on vacationstogo.com with a search for antartica you will find it priced at 905$ per person. It is the same trip as you searched but with an extra travel of 4 days to the tip of Antartica. If think it is a great opportunity to see this frozen land at a low cost and maybe some wildlife. The february 14th departure is the last one before the austral winter. For me it is really a dream destination!
How have you done for the payment the last time you shared a cabin?