Enkei Racing RPF1 Bright Silver Paint
13.7lbs $219
O.Z. Crono HT Bright Silver Paint
15.5lbs $203
O.Z. Ultraleggera Black Painted Also comes in bright silver
14.8lbs
($203) $184 - On sale!
That's what I see at tirerack. I didn't search other places, just use them as a ballpark. Everything else was 18lbs and up, except one other that was 17lbs.
Lightweight doesn't come cheap. Search craigslist (use crazedlist, it'll search the whole country) to save money. Personally, I believe in lightweight rims. I have 2 sets of rims both 16" for my GP, and the heavier ones (about 2lbs each) is noticable when I swap.