I have suffered from that disease from time to time. What I found to help is my mindset. The antidote is the following mantra: "I do not need anything from the quilt store/show. I have no need to buy anything. I will not buy anything. I am not even taking the checkbook so I CAN'T buy anything!"
Guaranteed - you'll find something you can't live without and on the rare chance that you really don't find anything - it's OK.