Most of the time if the damage is around 70% or more of ACV (actual cash value) then it's considered a total loss, but ACV isn't necessarily based on KBB values and the percent can be lower or higher, depending on the insurance company. If the ACV of the car is $3500 and it was totaled, you're possibly looking at $2500 worth of damage, but that's dependant on what the insurance says the ACV of the car is. Something that you would pay $3500 for may be worth much less to an insurance company. If they only valued it at $2000 then it could have been totaled for as little as $1400, there are a lot of variables to consider, what you pay for it isn't always what the insurance values it at. When you start talking about re-sale value there are a lot of variables to consider as well. Like Catnip said, it varies by car, miles, mods etc. Based on the limited information given and your estimate of $3500 value, $2500 or less is all that I would pay. But then again that's highly dependant on other factors, give us some more details on the car and we can give a little better answer.