For starters, Square Enix has just revealed that Final Fantasy 4 is headed to iOS later this month, on the 20th. A port for Android is also in the cards, but won't be here till spring of next year.
According to Touch Arcade, it appears to be a port of the recent Nintendo DS remake, similar to the iOS port of part three. It will also have a final asking price of $17.99 after an introductory launch sale.
Speaking of, Square Enix is also having a sale on their current iOS offerings. Up for grabs you have:
December 7-14
Final Fantasy I – normally $8.99, on sale for $3.99
Final Fantasy II – normally $8.99, on sale for $3.99
Final Fantasy III – normally $15.99, on sale for $8.99 (iPhone, iPod touch)/ $16.99→ $9.99 (iPad)
Final Fantasy Dimension – normally $28.99, on sale for $16.99
December 12 – January 7
Lara Croft and the Guardians of Light – normally $2.99, on sale for $0.99 (iPhone, iPod touch) / normally $5.99, on sale for $0.99 (iPad)
Victorian Mysteries: Woman in White – normally $2.99, on sale for $0.99 (iPad)
Victorian Mysteries: The Moonstone – normally $2.99, on sale for $0.99 (iPad)
December 17 – January 7
American Mensa Academy – normally $4.99, on sale for $1.99 (iPhone, iPod touch, iPad)
Given how Square Enix's offerings are so expensive, now might be the time to finally nab those titles you've been on the fence about.