Like RCT, I letter all of my "collector" purchases which is the vast majority of my purchases. I also search for the accoutrements for the firearms I purchase (holsters, cartridge belts, etc). Those are almost always much more expensive than a letter, so getting a letter is the cheaper and easier part of "collecting".

Before I was a collector, I just bought an occasional firearm that caught my attention and I never lettered those. In those days I also shot some of the guns I purchased, now I never shoot my "collector" firearms.