Of course it's a scam. Ask yourself, why would someone buy a used car sight unseen and pay extra to have someone come get it. Would you have done that?
I have sold many used cars in my day and as recently as last month. If the buyer does not want to meet with me, check out the vehicle, bring cash, then I will not talk to them.

As a side note, I hate it when people respond to a listing online and their first question is, what is my bottom line. I has no interest in negotiating with someone who has not even seen the item i'm selling.

I sold the car!

I'm sorry. I sold the car.

Sounds shady. IF someone gave me that offer, I would only agree to meet at their bank and have that person give me a check or cash from that bank. Bet the person will not agree to that.

Save some headaches - go to carman
 

Save some headaches and go to a dealer or CarMax and sell your car out right. I've used CarMax twice and been pleased with the transaction. May not be the best price but no hassle. You walk in with the car. They look it over and offer a price. If you like the price, walk out with a check. Easy!

I once sold a car to Carmax. They gave me a written quote that was good for 7 days. It was more than I expected. I would never try to sell a car to a regular new car dealership.