Built a 1 acre pond in NE this Spring for a client at $8k including core trenching and clay compaction 3 6" lifts.
Built .4 acre and .3 acre pond adjoining for $5k in 2009 including $1,600 in agridrains. So labor was only $3,400.
Just providing some comparable pricing to help you assess. $40k is ridiculous IMO.