Alpina do a straight carbon fork designed for track racing, it has a 1" alloy steerer and retails at £99 or approx $175.
www.oldhamcyclecentre.co.uk has them, and I'm sure there must be a dealer for them in the US.
Track cycling has a Ridley straight carbon fork also for £110:
http://www.trackcycling.co.uk/shop/search.php?c=fork
Again it's another UK site, but once you take off the 17.5% tax, the charge for delivery and customs might not be so much.