That doesn't look legal to me.
1.7?

Well the reviews may be made up. And the reviews all have different softwares in their descriptions.

1. I don't think Esoteric has granted any third-party seller/retail rights to anyone. Notice the version he's selling is 1.7. Spine is now at version 3.1.05.
2. The site also looks very shifty. It looks like there isn't even a way to report the seller for fraud. And make no mistake: everything else, the numbers, mentions of "global" and "San Francisco", the obviously fake reviews, are a con. They were designed to suppress your suspicion and gain your confidence.
3. The seller's collection looks like they were just torrented and sold at a price. Look at those prices of known software. Pretty sure that's pirated stuff, and he's profiting from it. You could illegitimately and illegally download all the same things yourself for free if you wanted. Don't do that, obviously.

There are many sites like this out there in various languages. And many independent developers of plugins, custom tools, and whole software have suffered because of it.

The only place selling Spine is esotericsoftware.com. That link is certainly a scam.