Good luck finding them.
Those covers have a nasty habit of falling off as you toodle along on a bumpy road. The cause is the owner's failure to replace the hold down clips at the rear of the fuel tank. Someday, he's riding along enjoying the scenery when he hits a little bump that causes the tank to lift a little bit(more than 1/16") and unbeknownst to rider, the top of the battery cover flops out and it becomes a piece of roadside litter.
If you are able to find any pre-enjoyed covers, protect your investment by attaching them to the bike with leashes.