I'd be skeptical too. It looks like a trike kitted Yamaha Morphous clone. The
Morphous is only a 250.
The only Chinese scooter I have ever known of that looks like this is the
300cc ICE BEAR seen here in this youtube video.
I believe that is what the guy is trying to sell to you. I don't think anybody
is making or ever has made a 450cc scooter... 400cc, 500cc, 600cc, 700cc
yes, but no 450cc anywhere. Can't find much about the scooter beyond that
video.
This is what I found
Huzhou Daixi Zhenhua Corporation
Their website is incomplete
http://www.zhenghuagm.com/
AND
http://www.ecvv.com/company/ivy_han/profile.html
Which is different apparently than the corporation listed above it.
Odd, but it might be an associated arm of the same company. Who
knows with global trade.
If it were me, a scarce china scoot would not be something I would
consider. Maybe one that is more common with the issues known and
parts relatively easy to procure or even a Japanese bike. This scoot
might be offered for cheap, but you might be stuck with a garage
queen/lawn ornament if you can't find parts to fix it when the inevitable
happens. just sayin.
I even wonder how difficult it might be to get ICE BEAR parts.
Maybe others here could tell you about that.