Frankenstuff (on this forum) sells new covers (he pops them) and will have K7/K8 covers within days I believe. I believe he wants $75 shipped - check the "bikes and parts for sale" section of this forum. The original ones are typically brittle if not already broken. The newly popped ones are better materials and you don't have to rub your rabbit's foot before you check your oil.
I have a K1-K6 set from LPM Replicas (in the U.K.) that are really nice and feel ultra rugged. I think they make K0, K1-K6, K7/K8 but are much more expensive than Frankenstuff especially when you consider shipping.
I agree with KCC. I have a Maier set with the odd mounting system. I don't like them. I put them on my K6 and had to bend the flange of my oil tank to get them to sit anywhere near flush. You can bet I regret bending my oil tank.