I was just getting ready to post this. You get the drink under Cheers, but you still need to pay for the cup and it is the cup that sends the price north of $20, not the drink. So if you order a $12 drink and the total is $23, you'll be charged $11 for the cup. (Same holds true for the "shots" they sell in the MDR, you have to pay for the souvenir shot glass but not the contents.)