I recently bought a Chinesium setup off ebay, came to $200. Certainly not BMW quality, but WAY cheaper. I got the frame:
Fit For BMW R18 Classic 2021-2025. 1 x Bracket. We are committed to resolve all issues in a friendly and satisfactory manner.
www.ebay.com
And the Windshield:
Fit For BMW R18 Classic 2021-2025. Windscreen will deflect more wind for a more comfortable ride. Windshield Color: Clear. Windshield Height: approx. 1x Windshield (As Picture Shown). This Screen for Motocycle is with efficient design and gives improved wind protection.
www.ebay.com
Now, the seller sent me the wrong windshield at first and it took almost 2 weeks to sort that out, but other than that, decent experience.
The install went well and I will see how it holds up over time. The only bit of the kit that was sub par were the windshield grommets, if they fall apart I can get some better ones. Also, the adjustable feet that lock into the top of the forks spin a little too easy, I had to add loctite, but I pretty much do that to all bolts I add to a bike anyway. Looks like stock, chrome looks good quality.
Now, just like stock the buffeting is stupid from this design, so I cut a slot into my windshield about 1.5" high just above the frame, most of the width across at that point and it helped a lot. Generally not a fan of windshields, but I need one if I want to ride this bike to work to put my parking sticker on. Going to keep messing with the aero on this cheapo windshield and see if I can get it to be a truly clean flow, if not, I'll get one of the aftermarket shields and mount that up.