The most you could legally get is what the current value of the shirts were at the time they were lost, which--since they were not brand new--would be less than replacement value. You are only entitled to the current fair market value of destroyed property, and you cannot recover additional compensation for the other party having wasted your time by not immediately giving you what you want. And to get this, if the cleaner doesn't pay you voluntarily, you'd have to sue them, which would cost money and take still  more of your time. You should probably take their offer, then find a new dry cleaner.