I've attempted to sell a product on Flippa before... Buyers are pretty skeptical especially about revenue and traffic.

You generally need to have some proof of revenue and that it's continuing to generate income, leads and traffic prior to the sale.

Trying to sell a product that's been offline for weeks is going to be an uphill battle unfortunately. On auction sites like Flippa for instance most of the buyers are SEO-focused so 2 weeks of downtime is going to be a liability.

If you want to sell it getting it back up should be a priority

On a market place like flippa that's killing any chance of a decent valuation, I'd work on getting it back up ASAP