My lfs shop may have a good way for a big pond and fairly cheap. He has a tetra pond liner that would make a 12'x9'x2' pond for $350. The liner material feels heavy. He said stack cement blocks 2' high around the perimeter pour cement down the holes. Put the liner in, anchor 2"x6"s around the top to hold down the top of the liner. That's about it. I don't know the brand,but he uses filters that look like barrels. The heater would be another thing. He suggested a small hot water heater may work. He didn't heat his. A 12'x9' pond would hold some big monster fish.