Yeah you can't get just the lever. If you want the whole switch assembly and the cover on top, you can order it from HP M0E29-67065 $169.72
I recommend to open the cover and remove the assembly. Now depending on how it looks, maybe drill holes on both pieces, put in some steel stick, glue it tight and put them together.
Or something similar. If you want to go all mad max just replace the lever with a screw.