That looks like a nice $100, not running, maxi.
If you check the engine out and it has problems. No compression or sounds rough. Then less.
If the seller won’t budge, tell them to get it to run and call you back. Even in perfect running condition, it’s not worth $500. Looks like it has cosmetic issues too. The luggage rack is bent from passengers riding it and the throttle grip seems to be missing.
I know it sucks, because some dope might buy it out from under you before the seller brings the price down.