I actually considered one of those. The Bestem is even a touch nicer trunk than the Sears / JCW, IMO. I had one previously on my VFR (since sold-off). The downside to the Bestem trunk is that they reversed the latch mechanism as compared to the GIVI, (maybe to avoid lawsuits?) so it will not fit right on a GIVI monokey mount plate without some modification of the GIVI mount (mill a hole through it) which may weaken the latch tang.
The steel plate that they ship with the Bestem is also nicer than the crude one that comes with the JCW, but I wanted to be able to switch between the el-cheapo and one of my other GIVI boxes, so didn't want to use the (reversed) Bestem plate.