Found them... Ordering now.
Smarter Shopping, Better Living! Aliexpress.com
nl.aliexpress.com
1) Nice find! I had looked at AliExpress myself yesterday, but didn't see any.
2) I hope they work, as they're fairly expensive: $69.30 + $109.12 shipping = $178.42.
3) I have the same (apparently unanswered) question that appears twice on that page: "How doesn’t [sic] the lower support connect to the passenger footrest?" I think the intent was "How does ...".
Nevertheless, as at least part of the bracketry connects under the grab rails -- which have very large bolts -- it's probably solid enough.
4) If you'll be getting Shad side cases, as shown in the sample pics, you might want to peruse my Shad 59X purchase:
Recently (just before a couple weeks' non-moto vacation), I installed a Shad 59X top case on my '23 C 400 GT. I had the OEM luggage rack and the OEM top case already on the bike, as part of my original purchase, but wanted more room (for two-up helmet storage for day trips, or just generally, for solo multi-day out-of-town trips) than the 30L of BMW's case.
For those interested in this subject:
1) I started out by following HedOpp's instructions for mounting the expandable Shad on the stock luggage rack: see
www.youtube.com/watch?v=YJCL0Euh2L0
That worked out okay ... if you never...
While you won't be adding a 59X, my point here is that I paid right around half of what ShadUSA wanted, by purchasing that top case from Motostorm, a reseller in Italy.
==> I THINK <== that the cases shown in the bracket ad are Shad SH23.
These are $229 minus 20% off for Black Friday (code BFSHAD, with an unspecified expiration date) plus shipping:
https://www.shadusa.com/products/d0b23100?_pos=1&_sid=2a6d5d2eb&_ss=r
Or $250 at Amazon (with free shipping, at least for Prime members):
https://www.amazon.com/SHAD-D0B23100-Side-Cases-Black/dp/B072WDVRKP
Or €167,00 ($174, but always deal in Euros when shopping at an EU site) + €60 shipping, for a total of about $236:
https://www.motostorm.it/en/accessories/luggage/shad-sh23-side-cases-black.html . My experience is that if you visit Motostorm's site several times, over a day or three, you may get a coupon code, or a lower price, or both.
Edit: I just looked again, and they're now €156,72. But then, at checkout, even less, about USD 196 total:
The differences here are nowhere near as dramatic as was the case with my 59X, but I thought I'd point all this out, in case you were interested, or perhaps if ShadUSA charges an exorbitant amount to ship to HI, etc.
5) IMO, 23L is a nice size for side cases. I have 22L Givi side cases on my Meteor 350, and they're serving me well (although they certainly can't hold a full-face helmet).
Good luck with your project, and I expect to read updates from you as it moves along.