As many others have said, a solo trip is very liberating. WDW is the only place I seem to relax but my one and only solo trip proved that I really wasn't that relaxed when I was trying to organize...
I have two favorites. One Eeyore shirt that says "I'd look on the bright side if I could find it!" and a Tinkerbell shirt that says "Mood subject to change without warning."
I usually need 30 items to bring back to work. Once I asked a CM at an Animal Kingdom shop if I could purchase 30 of the Disney Conservation Fund buttons at $1 each. A little more expensive but...