What are you going to do with the boat?

If you just need something to get ahsore from a close in mooring buoy or nearby
anchorage, you could make it back and forth on a couple of innertubes bridged
by a plank.

The website you linked answers your question for you. Every single one of the
so-called "testimonials" reads, "I really appreciate the prompt manner in which
you shipped the boat." The two on the home page even contain comments like,
"If it holds up over time it will be a great value". Nobody seems to have
actually used one.

As for the "testimonials", ask yourself:
Do you routinely sit down and crank out a letter heaping praise on a company
that has done nothing, so far. except get FedEx to deliver a parcel on time?

Check out the wholesale page. Sea Dragon is probably just one of the "Custom
names" available for a one time set-up fee of $200.

My guess is that these are cranked out in some sweatshop in Asia. (Several of
the better lines available these days are made in Italy). When one considers
the actual cost of raw materials in a 9-foot inflatable, most of the cost is
labor and most of the price is markup.

For performing duties where an air mattress or an inner tube would serve almost
as well, you can buy anything.
If you will be in situtations where a wholesale failure of a glued seam (that
could result in a swamping or sinking of the dinghy) might actually put you at
some serious risk, I'd step up a bit and get a product with at least a known
track record.

By the way, those prices are not "twice lower" than Zodiac, (whatever that
means).
Zodiac has some promotional boats that are commonly available for just a little
more than the prices on that web site.

Zodiac isn't the absolute top of the heap in inflatable quality, anyway. Want
to see some serious inflatable boats?

www.westcoastfrogs.com

Check out the Zar boats on the last page.
You could take one of those almost anywhere you had enough range to go.