Scratches on the lens can be mitigated by using a lens hood to block stray light and avoiding shooting directly into the sun; in fact, I would take a small scratch on one of my Nikkors over shooting through a budget filter any day of the week.
Lot's of good advice on this thread. My only thought would be: cameras come and go, lenses are forever. I run 1960 vintage Nikkors on my Nikon D1x made in 2003. Also, if you are buying lenses buy the fastest lens (biggest aperture) you can afford. Depth of field control is the key to truly fine photography.
