There is no universal list for how much salvage value would be, it depends upon the car and its damages and how much it is worth in its current state after being found a total loss.

Your insurance company is offering to sell you back your vehicle for salvage value. Normally salvage value is the amount of money the insurer would recoup when selling the vehicle through a licensed salvage vendor. So instead of selling it to a salvage vendor they are allowing you to buy your car back, get the needed repairs and drive it again.

So it would appear that your insurer has calculated your particular vehicle's salvage worth to be $650, you will need to determine if you believe you want to buy the car back for this amount and then money into repairing the vehicle to make it roadworthy once again.

Keep in mind since the car has been totaled out that most states will require it to have a salvage title and many then require you to get a rebuilt title once it has been repaired and found to be roadworthy. It can be difficult to find insurance for a car with either a salvage or rebuilt title and the car is worth less now as well since it has been though a major accident and totaled out.