Depending on the material MX-4 is produced with, probably aluminum oxide, I'd assume it be priced at 8$ or so. It shouldn't be higher since MX-4 should be a replacement for MX-2
Brand new in retail packaging, tested for DOA, and put right back accessories, etc in perfect unused condition. The dual fan version. Hasn't been registered with warranty yet, so you would still have 30 days
The mirror finish is just for aesthetics, if you really want it, I think you have to get some sort of liquid/residue that you wipe with cloth to make it really shiny.