I did the same, the first wheel within 2 weeks of getting the car and then just after I had forgiven myself I did it again with the other wheel, I couldn't believe it! Like you I usually give curbs a wide berth! The wheels aren't in bad condition but have decided to get them refurbished in a few months and change colour, so can't just do the one wheel (now 2 wheels). I spoke to the Huddersfield BMW dealer and they charge £80 per wheel (inc VAT), or there is a company in Morley that I was going to speak to. However to tide me over I have bought some Alloy Repair off Amazon, supposedly for factory BMW wheels, I guess that means the silver will be the same colour and I'm going to give that a go. I don't imagine that I'm going to be following the instructions to the letter as the curbing isn't really that bad and in fact if it was a bit smoother and painted silver probably would only be noticeable by me (although I guess that's the whole point). Anyway it came today and if it's really easy and looks fantastic, I'll post some pictures of before and after, but more than likely this is just going to be an easy bodge job that will force me into getting the wheels refurbished sooner than expected!