A good example of "charging by value" is productized consulting - where it's a particular task, etc. that needs done for multiple customers.

Say you're really good with Postgres, instead of just hanging out a shingle for "any Postgres stuff?" you offer something like a one time $2500 "Postgres Performance Audit".

You get really good at this one thing, have a set bunch of scripts, very deep knowledge, predone report template, etc. and providing a bunch of value. So at the end of the day who cares that it only took you 5 hours (effectively making $500/hr).

Bunch of examples: http://www.christophengelhardt.com/ultimate-badass-list-of-p...