There are actually 7 rules, but you already have 3:

(1) Must be a Maiden.
(2) Must be 1st or 2nd up.
(3) Must be $8.00 or more.

Clues:

(1) Check amount of starts for each selection.

(2) The thing they all have in common happened at their first lifetime start.

Hope that helps.

Cheers.