wrong, but I thought they put a hold on a portion of your card. The amounts, as listed above vary by level of resort. The hold, if I understand correctly, blocks out that much of your credit card limit but doesn't in any way obligate you at that time. It just gives Disney access to at most that amount of money when they close out.
We actually had a three night stay at a value resort three years ago and exceeded our limit. It actually happened when we charged our Crystal Palace dinner, but they didn't stop that charge. A little later my wife was charging a tee shirt at POTC and they wouldn't process it. The manager was gracious enough to take us to a side register not in use and call the resort to have more money placed on our account. She processed our purchase there instead of holding up the line. I'm grateful for that type of customer service at Disney or anywhere.