We sailed the 8-N Magic Southern Caribbean RT San Juan for under $3200 fare and taxes in a GTY oceanview. Ended up in a great location on Deck 2 Forward.
Booked it ~ a month out.
If this 10N cruise appeals to you, consider keep your calendar clear and watch for a price drop.
$12K is crazy / $600 pp per night?!
The slate of cruises from San Juan last May were bargain priced (for a Disney cruise, at least). That certainly isn't the case this year. Nor would I expect any cruise during peak summer, especially one from PC, to be offered at a steep discount.
Unfortunately, the only true bargain (for a Disney cruise, at least) cruises these days are the repositioning cruises. The low cost is often negated by expensive one-way airfare.