Fried a custom prototype .... Damage: About 100 €
Wow - you got off easy. I'm guessing your employer is enlightened enough to include plenty of spares in the order for prototypes. (My employer's purchasing department will only allow us to order the minimum quantity accepted by the board maker. This usually means we have only 2 or 3 spares.)
I hope your dad didn't get in too much trouble for blowing the channel on the scope.
The most expensive equipment I blew up wasn't my fault. The PCB layout engineer changed the orientation of a square micro-controller by 90 degrees but forgot to update the board markets. When a technician installed a socket where the micro would go, she followed the board markings. When I got the board and plugged in the in-circuit emulator, the emulator's interface "pod" belched the magic smoke when I powered the board. That was only about US$2000 to replace.
A co-worker of mine was once subject to the same "fire works" due the same mistake (by a different PCB engineer), but the damage was US$30k.