Just thinking out loud here really but if you stock up frost emblems and then the day before justice points are released use your frosts to buy primoridial saronites then log off. Log on and sell them back to the vendor for x amount of JP.
Checked mmo champ and saronites are worth ~230 JP but 23 frosts are only worth 63 Justice points. If it doesn't work, hey, you have some saronites if it does then hey, almost 4 times more JP.
If I am hideously wrong then sorry for wasting your time, pure speculation.