We saw that another company made them and that the demand was very low. Also in the case of the 10 bolt being nearly round makes for a very expensive cover.
In 2006 I worked alone and demand drove me whichever direction that was busiest. Now things are vastly different, however the demand is getting even lower.
I would have thought the companies that specialized in the rigs that had them stock would have made them by now, like DIY or ORD? Why have they not made one? Same reason I would guess...