Rota sells lightweight affordable wheels..
their lightest model is called the Slipstream..
11 pounds a piece for 15x6.5' wheels..
I have the 16x7's and they weigh 13.9 lbs.
www.18racing.com
the most direct way to get the best pricing,
I went directly to the importer of these in Hayward CA to get mine..
www.rotawheels.com for more info..
www.wheelweights.net to see how much they weigh..