2003 Audi A4 Grinding noise

OK. Me and my girlfriend were leaving the river Sunday on a dirt road and the car bottomed out. Not very badly either. We were doing maybe a half a mile an hour. We then drove to my house without incident. Then on her way home she noticed a grinding noise. She took it to a mechanic that her father knows but he did not have the equipment to diagnose it. He reffered her to another place that just happened to be a transmission specalist and of course he is saying its the transmission and that it will cost 1500 dollars to fix.
I was in the car when we bottomed out and I just have a hard time believing it could have done this.
I think it is more likely that something could have got bent and is maybe rubbing on the drive shaft, even though I have not been able to look at the car since this happened.
Please let me know if he is trying to screw us because we do not have 1500 dollars.