Many guys can move dirt, a few can dig ponds that hold water. When you are getting a good pond builder, you aren't just getting a guy on a piece of equipment, you are paying for the knowledge that he has to properly dig a pond too.
So true, and to do it yourself you need to learn all this stuff ahead of time.
I had begun mine before finding PB. I was looking all around for advice before starting, without luck. You have already begun your pond adventure way ahead of most people by finding this site. For you and any newbie that might be reading this, I can't stress enough the importance of patience and doing research thru this site. The more you know about structure, habitat, types of fish you eventually want, soils, dams, water discharge systems, etc, etc, the better off you will be when your in the process of actually doing it. Even if you eventually hire it out, you'll know more about what is right/wrong and the quality of work they are giving you.