Rick, one thing to consider that is not size related in the excavation bid. It cost's the same $$ to transport and remove heavy equipment to a site, and with todays tough legal permit environment, it ain't very cheap. I don't see it costing 6K, however. Ask what the operator charges "per hour" plus his transport costs, minimum job charges, etc. I wouldn't think a 1/10 acre pond would take more than 10 hours unless soil conditions, access and terrain are a real bugger....or, if extras like rock lining are involved. In Missouri. $100-$150/hr equipment rates are common depending on equipment size.