WHAT!They want 750 plus taxes to fix.!!!??
That's a ridiculous amount of money to replace an ignition switch. It's quite a simple job that shouldn't take a professional vehicle technician any more than an hour to complete. And I don't think an ignition switch is a very expensive part, even at main dealer prices. And an aftermarket one is only $14 at AutoZone.
I've never had to replace one on your particular model of car. But like I said, it's generally quite a simple job so if you know how to use a screwdriver you could probably do it yourself. Looking at the photo at the AutoZone link, it looks like the switch is only held on by a single screw. Disconnect the switch harness connector, undo that screw, and withdraw the old switch. Refit in reverse order. The only thing you need to check is that the new switch is in the off position (fully counter clockwise) before inserting it into the steering column.
And let's just hope the dealer's diagnosis is correct, because your own test seemed to show that the ignition switch was working properly...there was power on the orange wire at the back of the fusebox.