first u did 2 mistake.
1. let him go find his own workshop
2. did not check his damaged seriously.
How can you let him come back to you and say this is broken
etc.
You should have ask him immediately go to ur workshop or any
workshop if u don't have one to inspect and do a rough
estimation.
You let him opt. then no choice, he say $800, you have to pay or
even more you have to pay because you let him decide, not you
decide.
So next time be more wise.
just take as a hard lesson and gain your lesson.
Actually one thing is very important before you drive ur car. Be
street wise.
All the best.