I just fitted some tpi polorised bolts - have a look on their website - sell normal bolts too of you prefer - taper pro company is called
I had some black ones off ebay a while back, they were pretty decent quality but the road salt tarnished them after 7-8 months. Currently trying TPI black ones and they seem ok and well made, not sure how they'll last either but they probably look the best out of the two sets I've had.
I just bought some black covers to go over mine. Cost £14 of Amazon and there a perfect fit. Maybe an option for you.
Thanks guys, I did consider covers, let me know how you get on with them. I like the TPi ones, do I need nuts or bolts?
I coloured mine in with a black marker pen until I can be bothered to get new ones. After 4 months they still look good with no rust showing through.