The CFI is all about how much work YOU put into it. You already know how to fly the plane, do the maneuvers, what makes it work, etc.

What you're working on with the CFI is how to teach these items, how to find information, where to look, etc. It's a lot of prep time and study on your own. If you do this, you go teach a few lessons to the instructor you're working with, take a few flights in the right seat while explaining what you are doing, and take the checkride. If you don't put the time in studying and preparing you'll spend more time with an instructor which will cost you more money.

I'd say for every hour I was flying with an instructor I spent 5 hours on the ground with him creating lessons, teaching lessons to his other students under his supervision, etc. Probably cost me about $1500 to get my initial. The CFII cost about $600 as a friend signed me off and I only had to pay for a few hours of flight time.