They were early game Pennant Race rewards so they were rare early and a lot of people have either locked them in or sold them off. Supply has dried up as no new ones are entering the game.
That also answers your 30k question, because thats the max a gold can sell for. Diamonds max at 1m (Wagner)
To your showdown point, both guys have sweet swings. Andruws is a bit long but it drives the ball super well especially yo right center. Damon's is that quick LH pull swing like Ellsburys/Blackmon