When I began purchasing pins at WDW in 2003, I decided to have a "rule for myself" pertaining to the purchase of a pin.
If it is an attraction, I have to ride the attraction.
If it is a hotel, I have to been in, or stayed at that hotel.
If it is a restaurant, I have to have eaten there.
Because pin shopping can be and is a pretty expensive part of touring the Disney Parks, it keeps the cost down (somewhat) for me.
I think that when I visit Disneyland, for the first time in July, I will stick with the same rule for Disneyland. Might I be tempted, otherwise, to buy every 50th Anniversary Pin that I see, and go home - in the Poor House.
Curious. Anyone else have specific guidelines for buying pins, or just buy what you like, or go broke, buying everything is sight?