My two cents would be to pay the Olin deposit ($1,500) and consider as a sunk cost (A bird in hand).
If you get the Booth Admit and you choose to go for it, $1,500 wouldn't matter in the context of your overall spend and in the long haul.
In making your choice also consider outcomes... (depending on how you plan to fund your education though). If you are thinking entrepreneurship post MBA you don't want to have significant debt stressing you out.
But if you are looking at Finance or Consulting roles, aggressively go for Booth regardless of their offer.