What's a realistic valuation for a website?

What's a realistic valuation? I've heard you can do multiples of x10 and x12 monthly income, but I feel like that's a lot, what are your thoughts?

It is a lot! No doubt about it. The valuation depends on a lot of different factors. The age of the site, how long it's been earning, the marketplace you are selling on, the types of links that have been built to the site are just a few. But 10 to 12x is completely realistic. I just flipped a site on Empire Flippers that was link built exclusively with a PBN for 17x last month. There are people out there willing to spend that kind of money on sites that are already ranking and earning.

Depends on how long its been earning
where the traffic is coming from
Also how well its optimized to earn
sites less than 3 years old
Id think hard of payng more than 6 times monthly earnings
But there are no hard and fast rules

proof of income, notarized

I don't think you really can say much about the growth. It all depends on site and how you generate your traffic.

and the x10 thing sounds more of a dream to me (for a starter)