In my opinion, there is one golden Disney souvenir rule. Now this rule will not necessarily save you money, however it could certainly save time and disappointment.
With all that being said, my golden Disney souvenir rule is simple. If you see something you really like, buy it!
You will know when you set your eyes on your perfect Disney souvenir! When you get that feeling, do not wait on your purchase. One reason is because it could sell out, especially limited-time or event merchandise. Another reason why to buy right away is because even though there are plenty of stores at Disney World, some items are unique to particular shops.
This rule can be tough to follow for those who usually overthink purchases, such as myself. However, when at Disney purchasing when you like something will save you from retracing your steps to find the souvenir again (learn from me).
Do you purchase right away when you see something you like or do you wait and think about it first?