Pre Order Mac OS X 10.5 On Amazon
is available for pre order from Amazon. It's listed as $129.00 and has free super saver shipping. You can also get the Mac OS X 10.5 Family Pack for $199.I'm holding off on ordering for the moment, hoping in will find a better deal. In the past Amazon has had cheaper prices on the OS, but I've seen some local stores match it.
Both the single and family versions are #1 on Amazon's best sellers list