Also, assuming you get your money in 24 months and using a discounting factor of 5% (which is either much too high or much too low), you are looking at a little over 28k, not 30k.
The product already had traction—actual users numbering in the thousands—and from the buyer’s perspective, it was cheaper and/or faster for them to buy vs build a comparable service from scratch.
Also, by owning tweet.photo outright, the new owners can bundle it with other complementary services in their portfolio.
There is a saying that there are two ways to make money in software: bundling and unbundling.
https://www.lawinc.com/twitter-vs-twitpic-trademark-dispute-...
It seems like a complimentary product to the acquirers other portfolio of products. So it's probably a no-brainer for the acquirer even if 'overvalued' by traditional MRR metrics.
All available contractors where already busy building a FB clone on a weekend.
Domains are typically either worth a surprising amount, or very little (always surprising to inexperienced sellers). The gap inbetween tends to be very large. That's the common result I've seen most often over multiple decades of buying and selling domains. It's very common for people to think they have a valuable domain, and then inevitably it'll end up being worth a small fraction of what they think it is. Valuable domains are almost always super obvious (eg tweet.com would be), or otherwise you get lucky with someone that'll pay a few times over fair value because they've got a specific use case and really want it (eg tweet.photo is worth $750 if dropped on the market, someone pays you $2k-$3k because they have an idea for an app and that's in their mess around price range).
There may be nothing more annoying in this world (joking here) than the domain squatter sitting on a $300 domain that is fully convinced their domain is worth $100,000 or more. It's their chance, their lottery ticket, and they're not selling cheap. Back in reality, exceptionally few domains are worth more than a few thousand dollars.
I just want to add that while it might be possible for you and me to "build this in a weekend" (although in reality it always takes longer considering all the edge cases), for other businesses it might be cheaper than just buying an existing app. They know what they are getting versus hiring a freelance developer, writing a spec, managing them, etc, etc.