So let's value it as it would be valued on, say, Flippa, a decent proxy for "the market." We would look at the monthly revenue: in this case, around $750/mo (which is 9k divided by 12). Then we'd do a multiple of the monthly revenue: 20 is low, 40 is normal. I would actually say 30 here, because this guy created the asset and I would bet he did it well and it's not junk. So let's say it's worth $22.5k.
So I think it would be more accurate to say, "I purchased the site in a deal through assets valued at about $42k, total."
[edit: updated the comment as I got confused about the thing being exchanged - it's a site the guy created that he transferred to make the sale]
In particular, if someone on the internet tells me they’re making $x a month from spammy ads on a squatted domain, I immediately discount the claim substantially due to bullshit. I increase the discount rate if the person making the claim is trying to sell me said domain.
Enough to be motivated to proceed with due diligence.
Whatever any potential buyer considers that to mean for them.
How much are you trying to sell the domain for?
Uhh...about $100k.
That's obviously an upper bound, because those domains won't make $9000/year forever. But valuing them at $10k if they make $9k/year is equally unsound. Not to mention the domain is worth more than its ad revenue. You could also end up selling it to a company that came up with the name and saw that the domain is available for purchase for some reasonable 4-5 figure amount (like in the example of this very article, where someone buys a domain for a five-figure amount)
Obviously there is a lot we don't know (is the $9k pure profit or are there substantial costs? How likely is the domain to sell?), but it sounds like the seller got the better end of the deal. He got more than $40k in value, in return the author got a deal he could afford
The buyer takes on substantial risk because it's easy to fake the numbers, and google updates can tank the site at any time.
Also, most sites will require maintenance/upkeep to keep earning, or they can tank quick. Even if they have got evergreen content, without updates google might drop their search ranking.
You can’t just send tens of thousands of emails via your typical email service.
Also, even if it were making about $9k/year in profits, if that comes with large costs (be it labor or dollars), it still might not be worth it. Let’s say it costs $100k a year to keep that site making $9k in profits. That would be 9% return on investment. Good but not spectacular. Add in uncertainty about whether that site will keep doing that, and I can see such a domain not being worth much.
That's not investment, that's just the cost of upkeep. It's possible you simply cannot afford to keep up with that expense rate, but the fact remains that it's net profit. With a $100k investment and a yearly $9k profit, if you stop at the first year you lost $91k. With a yearly $100k cost and a yearly $9k profit, if you stop at the first year you earned $9k. No matter how you slice it it's a money-printing machine. The question is much it cost you to buy the machine, not how much it costs you to run it, because you'd be a fool to turn it off.