Mr. Grey paid $26/shirt x 3 shirts = $<<26*3=78>>78 on polo shirts.
He paid $83/necklace x 2 necklaces = $<<83*2=166>>166 on necklaces.
So, he paid $78 + $166 + $90 = $<<78+166+90=334>>334 for the gifts.
After the rebate, the total cost of the gifts is now $334 - $12 = $<<334-12=322>>322.
#### 322