I don't use thimbles. I use what I know as "finger tape" its a mesh type roll. I know it comes in green or white as those are the only colors I have ever used. I used to use it when I worked in an electronics manufacturing company. It is used to protect your fingers when doing repetitive moves to help prevent blisters on your fingers. Just wrap it a couple of times and squeeze it onto your fingers. I've used it for years. Here is their website if you want to check it out.
http://www.generalbandages.com/
GUARD-TEX® Self-Adhering Safety Tape is the wrap-around tape that . . .
Guards hands, fingers, & wrists: Protects skin against rough, sharp, or hot surfaces. Prevents small cuts, abrasions, and minor burns. Eliminates sore and tender fingers.
Sticks only to itself - not to skin, hair, clothing, or tools. Always easy to apply and painless to remove. Leaves no gummy residue.
I noticed that they don't have the prices listed so I suppose you need to call them. Its worth checking out. And you never need to keep track of your thimble. Just go around your finger a time or two tear off and squeeze it on the finger.
Edited to add: I also use it on my fingers when I am going to be cutting out alot of fabric. Helps prevent sore spots from rubbing on the scissors.