I think it's kind of a bummer that you had to start off with obsidian before you learned to visualize a piece of stone and see the possibilities within.

When I started flint knapping I took a course from a local primitive skills group. The instructor started the group off with glass, johnstone (porcelain HAHA), chert and some other types of stone that he provided. However, before even getting that far we learned about theory, terminology, different ways of flaking and abrading, and more, so there was a basis for understanding and knowledge for learning to build upon.

It sounds like you were in a class where the teacher didn't understand teaching.

Also, starting to learn flint knapping with obsidian that you had to pay for strikes me as similar to learning to drive with a Lamborghini. I know it would make me apprehensive.

Well... Maybe that comparison is extreme, but we don't have obsidian locally and it costs a bit to get a decent amount of good sized quality knappable stones shipped here. Chert is somewhat less expensive because there's a small supply within the state, but we have a number of glass workers that will give us slag for free or very cheaply, and we can go to a number of places and pick up porcelain for free as well. When it's free, you don't mind whacking it with a hammer stone just to get a feel for what's going to happen when you strike a platform a certain way.