I have my essentials config set up so everyone can do /back for $100 per use. When someone dies, it tells them that they can /back to get back to their death spot, so they do it and it takes $100 from their balance. Then, they get upset because if they had known about the command cost, they wouldn't have /backed.

I would like to suggest adding a confirmation associated with commands under command-costs.
So when someone does /back, it replies with something like "This command costs $100. type /back confirm to confirm"

Edit backAfterDeath in this file and place it in your Essentials directory, however its still a valid feature request.

aslong as it can be turned off im fine with the option for those that want to use the confirmation system

With the current way that confirmations and command costs work, this would need to be added on a per-command basis. However, I'm not opposed to changing these to allow this feature to work.