Cheapest 8x/8x board I could find.http://www.msy.com.au/product.jsp?productId=7556
32 AU lefthttp://www.msy.com.au/product.jsp?productId=4950
Puts you 83 AU overboard, but you get a good solid PSU for future CF and a solid motherboard for Crossfire.
The reason it's better to have a 8x/8x board, CF just loses WAY too much bandwidth and performance @ 16x/4x. Refer to this article. http://www.tomshardware.com/reviews/pci-express-scaling-p67-chipset-gaming-performance,2887-11.html
"More significant are the losses when using a x4 slot, as expected. The GeForce GTX 570’s relatively significant 9% performance loss is far exceeded by the Radeon HD 6970’s 18% loss."
18% is a lot of performance