I'm considering buying a competitor's shuttered digital storefront. How do I valuate it?

Competitor was never a competitor of mine, I started my business after they shuttered theirs 2 years ago.

However, they've kept the URL live with a closure notice and offer to sell. They have an established Facebook presence.

They claim to have regular enquiries via email — but this is not something I want to base my valuation on.

They've got decent SEO for the local keyword I'm looking for - bottom of the 1st page. I'm considering buying their URL and Facebook presence.

This is for a local service business, not e-commerce, so pretty narrow market.

How can I assess a fair price here?