Dorman makes an exact clone of the stock lugs, part #611294. The cheapest place I've found for them is rockauto.com.
RockAuto Parts Catalog
It is fairly easy to cut the top of the cap with a hacksaw, dremel or sawsall. Just put the lug nut in a vice and shave the very top. Don't cut too far down or you'll be cutting into the lug itself, although it's no big deal if you do just more work for your cutting arm.