RCI (or Manheim/BCA depending on who the car goes off to) can be very reasonable with damage charges. E.g. I believe the standard charge for a scuffed/damaged alloy is ÂŁ55 - you won't be able to get it sorted yourself for anywhere near that. They also charge about ÂŁ60 for scratches/gouges that can be fixed with a SMART repair - again good look getting it done yourself for that. They can also be flexible with what is/isn't wear-and-tear.
The reason for the low charges is that most of the time they won't actually get these repairs done - they're just pricing in the loss of value on the car when it goes to auction.
When I returned my Prius from its lease I got Chips Away to identify what wouldn't meet BVRLA standards. They quoted ÂŁ1190 to repair the damage (scratched bumper, slight dent on bonnet - from a roof tile, shopping trolley scratch down the side, numerous stone chips, etc.). I declined and took my chances. How much did BCA want for the damage when the car went back? ÂŁ0. "Won't have any problem shifting this one, mate", said the agent that collected it.