$2300 is reasonable I think considering the delivery charge for the machines, and the approx $1000 a day to run them with an experienced person using them.
If I were you, and you have the space, I would make it larger around since to hit your depth the sides will need to be very steep. It will look like a bomb crater. Get the book mentioned, and be prepared to spend the money correctly the first time, rather than several times and a lot more to get it right.
We are here to help you get a pond you want, is usable, and not a source of anxiety.
