Hidden somewhere in their knowledge base, the official pricing for Tabula Rasa is now available:

Players who wish to pay by credit card will be able to choose from the following recurring billing options**:

  $14.99 per month
   3 months - $41.85 (the equivalent of $13.95 per month)
   6 months - $77.70 (the equivalent of $12.95 per month)
  12 months - $143.40 (the equivalent of $11.95 per month)

Players who do not wish to use a credit/debit card can use game time cards, which are available at many North American retailers.

Original Source: http://help.plaync.com/cgi-bin/plaync.../std_adp.php?p_faqid=6160&p_created=1189531902