In either case there is both contract law and state federal law (unfair trade practices) that would support my claim in the courts if I were so inclined.
Was your recent sale grossly and clearly mispriced with evidence such as similar domains selling for many orders of magnitude more?
Who ever listed it agreed to the terms of service/contract multiple times and verified the price multiple times, it’s not incumbent on a buyer to point out to a seller their price is below market value (and that come directly from the case law for contracts). If there was an error (either by the lister or maybe a bug in the marketplace software) believe it or not the claim would be against them and not me, and presumably they would both also be covered by insurance specifically for those kinds of damages.
Im not saying I will take legal action, for example I offered them to just put my domains on their “premium listing page”. But I’m also not here to debate the legal merit of contract law.
As a person who misses a lot of flights, I can tell you that they can always reroute you, usually for free, and sometimes get you home faster, but if you're an asshole and constantly talk about how you've been wronged, you get to wait for the next flight.
I say this as someone who had their domain auctioned off when I was unemployed because I was too depressed to read my email and didn’t see the notice until I was out from my cave, losing a domain I owned since 1996.
I’m not in the side of the registrar, but no reasonable observer would think you should be able to buy ua.com for $78, so you haven’t done much in the way of “testing” by not being a high value customer, and by selling a domain that’s not valuable.
Of course I did that because I had just sold crypto comic book.com on their marketplace. And they refused to reverse my sale.
And you don’t think I did that ? Why would anyone make that up?
It’s really not on me to test the accuracy of a publicly traded company’s auction website or a seller who may or may not have priced their item in error. It would only be a moron who didn’t buy it under the circumstances, it’s not like I was responding to a Nigerian prince email, it’s a publicly traded company’s auction marketplace that claims to verify domain ownership before listing.
UA is likely a LARGE customer of the domain service you use and pay multiple thousands of dollars more for managed services and support than you do. They will get special treatment because it's in THEIR contract, just not yours.
Try reaching out to them and ask what kind of contract you need to sign to get the ability to reverse accidental sales, they probably can quote you a price.