Why not just give it away as a gesture of goodwill among Mac enthusiasts? Just have someone send you prepaid envelope and give the disc away, especially if you are not using it.
As for the second disc, I really don't know what to say about it. I just think what Apple is doing with iLife package is dirty, since all you are paying for is iDVD 3. Apple does have right to do what it wants with their softwares. But "i" softwares are consumer grade softwares and something they use to attract customers.
They have DVD Studio Pro which they charge people large amount of money. Compared to DVD Studio Pro, iDVD is a stripped down version much like the comparison between Final Cut Pro and iMovie. They don't charge people for iMovie, but why with iDVD? Is it because people can choose to upgrade optical drive without going through Apple channel whereas Firewire, which iMovie relies on, is already built in? But then people have to buy DV cameras anyway to use iMovie. The whole charging people for iDVD issue really does not make much sense to me.
I just hope it is not prelude to what is to come, charging people for all future iApp upgrades, including iMovie, iTunes, iPhoto and etc.