Yes I would buy the crashed car
So you would buy this wreck of a car. You perhaps know something we don't but to buy this car for 20% - 30% under it's roadworthy value would be second only to insanity.
It simply isn't worth more than the scrap value, which isn't the a lot.
So ok you'd probably pass on buy the whole car and let it go for scrap instead.
But wait
Would you buy the used premium tyres used on the car at 20-30% under the cost of a new set of premium tyres.
The owner says they're "good tyres no problem at all with them and a good few months tread".
Would you buy the tyres and put them on your car if they fit?