There are two ways of building a collection: thinking carefully of everything you want and buying them one at a time; and buying everything you can possibly buy and discarding what you don't want later.

The latter is more expensive, but it gives you more peace of mind. You have the benefit of experiencing all your purchases firsthand, and you don't torment yourself with ruminations such as "WHAT IF I bought the other one instead?"

Take care, though, not to have the same attitude toward people.