Sounds about right.
The sad part is it will only take someone about 3-4 hours if they know what they are doing. So that works out to be about $300 per hour with parts. Lawyers are typically not this much!! Most electricians typically charge between $90 and $125 per hour in this area last I was aware.
But I would rather try to credit the buyer the amount. This way you are not in a situation where there are surprises or someone comes back and "claims" it is still not correct. I would make the case this gives the buyer more options and allows them to get things done the way they want it done. You may need not bump up the number to $2000-$2500 as a credit for the buyer.
What brand of circuit breaker panel and circuit breakers are you dealing with?
Federal Pacific Electric??
http://swartzelectric.biz/why-federal-pacific-electric-panels-need-replacing/