"From the legendary blacksmith, Kururi-san himself."
I mean, it's not wrong. Not that they know that.
If she thinks he's the master of the shop, why would she insist on putting her name first?
"The Blacks Mith Shop of Ellie and Kururi"
What's a mith, and why are they black?
Why would he think they were business rivals if she's not a blacksmith.?
"If it was the legendary smith himself, how much would you pay?"
That argument only works for payment if he actually is the legendary smith. Or rather, that they believe he is, or that he is just as skilled.
He makes all the money, she makes all the decisions. Sounds like your average marriage.