Grand Vizier
+ 1 Action
Gain a Treasure costing up to 8$ - 1$ per card in your hand, putting it in your hand.
If you do, trash a non-Victory card from your hand.
4$ Action
Not necessarily better than Explorer w/out Province (Hand with no card you want to trash, hand size was 7 before, etc.)
Not necessarily better than Lookout (If you have all the good Actions and Treasures cards in hand or if you don't want unnecessary silvers, cannot trash estates)
Not necessarily better than Trading Post (Now trashes 1 card, no estates)
Not necessarily better than JOAT (Trashing isn't optional, cannot draw you 2 cards if you had 4 cards in hand before, trashes coppers not estates).
Is still a good opener if you want silvers.
Can trash its own gain in edge cases and when the only point of playing this was to set up another GV.
Cannot trash Victory cards because it looked really strong if that was the case. If you are suffering from discard attacks, you are discarding your Victory cards anyway and you almost would rather have estates than coppers anyway.
Doesn't gain a Gold even when 2 of these collide, requires 3 or more GV to gain golds, or another case where handsize is reduced (beggar, market square, discard attacks, minion, actions that decrease handsize, black market comboes, etc.)
"If you do" is there because all Treasure cards in the supply could be gone, creating an edge case where you can claim not to have non-victory cards. It can be easily replaced with "... or reveal a hand of all Victory cards."
Editted to in hand.