::ahem::
I do believe Intec makes controllers that use a lithium ion battery. Depending on which one and where you get it, they cost up to 50 bucks.
And even if that wasn't the case, you can but lithium ion battery packs for the PSP and DS for ten bucks.
And again, there is still no excuse to not include some sort of rechargable battery pack, lithium ion or otherwise.