Sit down! If you think the HRE's are expensive, you will find that light racing products cost a lot of money. The old racing adage; "how fast do you want to go and how much money do you have to spend?" holds true here, but there a some reasonable alternatives.
1. The lightest wheels that will fit the C5 are DyMag Special Magnesium (C4 offsets). 17x10" Fronts at 8.5#'s and 17x11.5" Rears at 10#'s. The fronts will hold up to a 285x17 tire within the wheel well and will clear the suspension and brake duct. The rears will stick out 1 1/2 - 2" but will clear everything with up to a 335x17 tire. Very rare and hard to get. $3500 per wheel! $14,000 a set!
2. The C5R BBS Magnesiums can be had either in the Single Spindel Nut mount like the C5R or in a 5 bolt street pattern. 10-12 #'s/wheel. Approx $2500/wheel !
3. BBS also sells a street Aluminum wheel, I think the LM (looks like the C5R) or RK model. 14-16#'s/wheel. I'm thinking $1,000/wheel, probably comperable to HRE's
4. Fikse is making a new modular wheel for the Corvette. Callaway used these on his C-12 LeMans car this year. Will be available to the racing public soon.
5. Jongbloed makes a nice Magnesium center with heat treated polished and anodized Aluminum rim modular wheel. 16-18 #'s
6. Kinesis and Circle wheels make nice lite racing wheels 16-18 #'s
7. My best recommendation for value and a relatively strong and lite wheel that looks great is the Complete Custom Wheel from Pirate Racing. CCW's look like the C5R's BBS but in a high polished Aluminum Modular. @ $1,700 for 4. 17-18 #'s. I highly recommend them and you can see them at
www.midatlanticmotorsport.com
Tom Reichel is a good guy and sells some great Hoosiers too.
www.bbs.com
www.kinesismotorsport.com
www.jongbloedwheels.com
www.fikse.com
www.ontrackproducts.com
(Circle Wheels)
There are of course others which have fitments for the C5/Z06:
OZ Racing
Tecnomagnesio
MMW
MWM and others but they are expensive and support is weak and availability scarce due to importing.
An upstart Australian Co. is also just coming on the market. Simmons Wheels thru Group A, Inc in Tuscon.
www.groupawheels.com
There is also Speedline
www.speedline.com