Personally I'd be very wary of Chinese mail order stuff after a mate bought a luggage rack for his Bee Em From Ali Ex (Or though it may have been Wish.com).
He had to file the mounting holes as they didn't line up, it was painted as opposed to powder coated and so scratched easily, and the welds were full of pinholes so bad they had to be filled with epoxy putty. He sold the bike shortly thereafter so I can't say how long it did or didn't last.
I'm not saying all Chinese stuff will be that poor quality wise, I've had the odd CNC alloy bits that have been fine but I'd be hesitant about risking fitting a load bearing accessory like a rack to my GW.
Another downside to ordering stuff from Chinese suppliers is the horrendously long delivery times.
Having said all that, I'm not sure where else you could try as I'm sure you've scoured Ebay etc by now. My 'Zuma had a rack and Givi box fitted when I got it so I haven't had to look myself. You could put a post in this site's For sale/Wanted section as stuff like racks sometimes comes up.