At least 5K USD and likely higher given the current AI hype and the obvious 'large language' interpretation.
It would've easily been 10x this value if only it had been llm.ai.
I know anything 'meta' is all the hype but you definitely got a good offer here. I would probably take it.
Also like Jannes said it does look like the MetaSky business is making an upgrade from the .me TLD.
If you're doubtful about the $15K you...