I have used these scratch free. They work fine and were problem free. You can save bucks by getting P-clamps and hardware at HD or Lowe's but how much do you intend to save on a $6 kit?? I can't see it being worth the trouble.

A search search should turn up racks that have legs that go over the axles. I have never used or paid any attention to that style.

The bike I am using a rack on now had bosses at the top of the seat stays, but I am using this seat collar. On this bike, with the rack that I have, using this collar just made everything look more "sanitary".