I don't think that there is really any set price for any domain. I mean you can only have set prices for things that are produced in numbers. Those are set by the market.
Of course there are always some previous domain sales which can give an approximate value to a domain, but its real value is what someone is ready to pay for it.
If you're lucky, you can find an enduser with lots of money (big corporations or billionaires) who absolutely want to have this particular domain. As each domain is unique, if you have great skills, you can sell some domains for an unbelievably high amount of money.
On the other side, if you're unlucky, you can have a really good domain but no enduser will be interested in it and you will only be able to sell it to a reseller at a heavily discounted rate just because you needed the money quickly.
$123,000 for a domain like freecreditscore.org is obviously overpriced and someone else might have sold this very same domain on NP Marketplace for $123. But as always in the domaining world, it's all about finding the right buyer at the right time... Not always easy but it can be well worth it...