NaN looks more like a glitch to me. Which made me close the website immediately. I’ve heard about their « contact us » model thanks to HN.
It's on purpose because the pricing model is still work in progress.
I might recommend saying "Contact us" or "Coming soon" – I also thought this was a glitch or that you were attempting to serve personalized pricing and it wasn't working.
"Contact us" to me almost always means "you're going to have to talk to a salesperson who's trying to maximize their commission." That doesn't sound like someone who's "buying domains for fun" would really want to do. It also adds a significant amount of friction to your customer acquisition process.
I agree, I also don't like it. "Contact us" has been removed