It's really not worth much. After all it is 40 years old. I'll give you $1200 for it.
In all seriousness... Crowns are very highly sought after by skoolies. Skoolies also tend to be cheap. The market varies by demand at the exact moment you're looking to sell. You might get $5000 for it. You may have to settle for half that. Depends on how fast you want to get rid of it. You "might" find a sucker willing to give you $10,000 for it. I wouldn't hold my breath if I were you. Plan on somewhere between $2500 & 5000.
Well, the driver's seat doesn't look stock. What drivetrain does it have? A/C? That kind of stuff will make a difference.