He may well be adding up the bills from the time he has owned the car i.e it's had three motors, 2 different brake set ups, 2 different diffs, blown 2 gearboxes etc, etc.
If that's the case a 55K spend is possible as you don't always get things right the first time and bits break.
Having said that I personally think "saying this build cost X" would be a better way of advertising it.
Matty