Perl flavor, 97 [cracked]
I'm afraid this is going to be too easy due to the key length limit.
^([^,]+),(?!\1)([^,]+),(?!\1|\2,)([^,]+),(?!\1|(?:\2|\3),)([^,]+),(?=.\2+$)(?=.\3+$)(?=.\4+$)\1+$
If you think you figured the idea behind it, try the longer version (not part of the challenge):
^((?:[^,]{3})+),(?!\1)([^,]+),(?!\1|\2,)([^,]+),(?!\1|(?:\2|\3),)([^,]+),(?!\1|(?:\2|\3|\4),)([^,]+),(?!\1|(?:\2|\3|\4|\5),)([^,]+),(?!\1|(?:\2|\3|\4|\5|\6),)([^,]+),(?!\1|(?:\2|\3|\4|\5|\6|\7),)([^,]+),(?=.\2+$)(?=.\3+$)(?=.\4+$)(?=.\5+$)(?=.\6+$)(?=.\7+$)(?=.\8+$)\1+$
EDIT: The previous one was accidentally too easy. This one will hopefully be a little more challenging (not part of the challenge, uncracked yet):
^([^,]{2,}),(?!\1)([^,]{2,}),(?!\1|\2+,)([^,]{2,}),(?!\1|(?:\2+|\3+),)([^,]{2,}),(?!\1|(?:\2+|\3+|\4+),)([^,]{2,}),(?!\1|(?:\2+|\3+|\4+|\5+),)([^,]{2,}),(?!\1|(?:\2+|\3+|\4+|\5+|\6+),)([^,]{2,}),(?!\1|(?:\2+|\3+|\4+|\5+|\6+|\7+),)([^,]{2,}),(?=.\2+$)(?=.\3+$)(?=.\4+$)(?=.\5+$)(?=.\6+$)(?=.\7+$)(?=.\8+$)\1+$