Umm, so what are left nuts going for these days? 
That is a lot of work that you were quoted for. Maybe do the major work (setback) this season and go from there one chunk at a time … 
We feel your pain. Good luck.
I am not bitching about the price. There is no difference from me buying a brand new 12JR for $6600 and have it show up in a box then still have to pay someone to install it. I do think I am getting a lot of work, custom work at that plus labor and the total is actually 5500 because I already have the hardened shaft and impeller. The only problem I have right now is convincing the wife to let me spend another 5500 after spending a couple grand more for the motor. If I can't get her to buy into it I have a mild 496 ok. It mild still kinda wild but my pump as is will handle the 550 to 600hp and then this winter have the pump built.