50% off sale on most Final Fantasy games on the PS store until 2/19/2013:
DISSIDIA 012[duodecim] FINAL FANTASY (PSP) - $9.99
DISSIDIA DUODECIM PROLOGUS FINAL FANTASY (PSP) - $1.49
DISSIDIA FINAL FANTASY (PSP) - $9.99
FINAL FANTASY Tactics: War of Lions (PSP) - $4.99
Final Fantasy (PSOne Classics) & Final Fantasy II (PSOne Classics) - $4.99
FINAL FANTASY IV: Complete Collection (PSP) - $9.99
Final Fantasy V (PSOne Classics) - $4.99
Final Fantasy VI (PSOne Classics) $4.99
Final Fantasy VII (PSOne Classics) - $4.99
Final Fantasy VIII (PSOne Classics) - $4.99
Final Fantasy IX (PSOne Classics) - $4.99
+a few more
Link
If FF5 and FF6 are the same versions that were released on the PS1 I would not recommend them, poor loading times and very frequent.