Welcome.... You found a great site with alot of information. Having said that, use it to do ALOT of research. The more you do now, the more money it will save you in the long run, and the better the pond will turn out. Purchase the book advertised here, The Perfect Pond.
My first thought is that you said 'dirt guy', not pond builder. A lake this size you better have a good pond builder. The bigger the pond the bigger the headaches can be, and the cost to redo it. I know you said friend, but sometimes it is best to look outside of that, even for just a second opinion. The price (Around 17,00?)sounds cheap to me (but don't know much in that area) for 13 acre pond. There can be alot of hidden costs that you aren't seeing yet.
