My experience with replicas isn't particularly good. I bought a set of 17 inch M5 replicas for my 330Ci. Admittedly, they were for my winter tires. Anyways, after one winter, I noticed that the finish was literally flaking off in large pieces. Anyways, I agree with some of the others who say the replicas are heavier. They are. Just another issue to deal with. I have FM replicas which are readily available on eBay from many different dealers.
However, there are many OEM wheels available on eBay, from people who have upgraded from their OEM to aftermarket rims. There are some very good ones out there. Just be sure about the bolt pattern and more importantly, the offset. Otherwise your bimmer will end up looking like a dune buggy.