Cuda,

I would have confronted him about your previous agreement first thing. Number 1 make sure the car is assigned to you, 2 sit down with him and discuss original agreement, hopefully you clearly spoke of the price you were willing to pay.
I placed a $1K deposit, non refundable, no options $42k, had them make me a copy of the von sheet, we wrote the amount on the sheet & we both signed it, both have a copy, case closed. I wanted the car and knew time was against me, so what do you do? Buy it of course.

Always remember anything to do with money get it in writing, don't be afraid it's your money.