Subscription prices are listed here. For Legacy, it's 9.99 for 30 days, 8.99/30 days for 90 days (26.97), 7.99/30 days for 180 days (47.94).

I went to the Support Center from the link in the upper right of the Mog Station and searched for Crysta to find that page.

So, standard sub, 30 days is 1499 Cyrsta. 90 is 4197 Crysta. 180 is 7794 Crysta.