I haven't read the whole thread, but here are our rules:
*It has to saw "Disney World" somewhere on it.
*Nothing I can buy at
Walmart for much cheaper.
*Clothes must be of quality. I can buy Disney World t-shirts just outside the world for a heck of a lot less (think $5).
*I have veto power, if I'm buying, over anything I just don't think is worth it. And I limit what I'm willing to buy.
*Any whining will not only NOT change my mind, but make me much less likely to say yes the next time. We have this rule at home--ask (politely) when you see something you want, look all you want, but when I say no, it's no and I don't want to hear about it again. Of course, my son usually comes back with a Christmas/Birthday list request. If he keeps seeing the same thing and wants it each time, then I know it is something worthwhile in his head--ie, Darth Vadar voice changer mask.
We also go over what we're willing to buy pre-trip. DS4 last trip (10 days) got to pick a foam dinosaur from AK (He's a big fan and they are nice), we do pressed pennies along the way (seperate out the pennies and quarters pre-trip and when they're gone, they're gone), Autograph book & pressed penny book, a magnet of Goofy, and a very nice shirt.