I wish I could remember who made it, but I got a cover at the NEC show about 5 years ago. I don't iike the usual belly-strap, so they made me one with a drawstring round the bottom, and could have put eyelets in if I'd wanted.
If you're going to any of the shows, look out for a firm who just do covers, and ask if they can make what you want. I remember they didn't charge any extra for it.