The 14x1.25 lug bolts are common to many BMW models, including the R56 mini. I happen to have an R56 mini race car, and bought silver bolts from here
http://www.lohen.co.uk/shop/proddeta...WheelBoltsGen2
That was convenient for me (I am not in the USA). I am sure there are loads of local places where you can get them.
Just google around and you will find some