Too bad the coin is all scratched up! Fewer than 15 in existence. I would have not let my child play with that coin at all! All I can do is https://sputniknews.com/europe/201610261046774467-rare-coin-childs-pirate-treasure/
Just to put it in perspective, 15 is the same number of known 1804 dollars. I could not imagine an 1804 dollar in similar condition selling for "only" $300,000.
I've the feeling their valuation estimate might prove a bit conservative when the coin actually hammers. Boningtons seems certain that it will easily break their house record of £200,000, and with the Pound being as weak as it is at the moment I'd be surprised if it does not double that.
Yes, despite the "battles" that coin's been through, it still is in amazing shape. Think though, that coin sitting there all that time.
U.S. coins are way overprised. I'm not surprised to see a foreign coin where only 15 are known to exist selling for that amount. There are foreign coins where less than 200 are known to exist that sell for only a few hundreds or a few thousands. If they were U.S. coins the hype alone would make sure they would sell for hundreds of thousands. Heck, just ask us ancient coin folks how many coins we have where only 10 or 20 are known to exist that we bought for $100 or $200. I passed on one the other day from medieval Southeast Asia where only 32 are known to exist, and the price for this nice rare silver coin was only $120. I'm kind of hoping to one day snatch one for a little bit less. We shall see.
The people who are willingly paying that money for them would beg to differ. As long as one person exists who is willing to pay more for that coin than you are sees it for sale, you will not get the coin. US coins are only overpriced for those who do not wish to pay what they cost; that's how "demand" works. If that sort of demand attended the coins you have interest in, they'd be "overpriced" to you as well. Count your blessings.