I have the opposite adapter. They should be somewhat easy to find. The reverse, which you're looking for, might be a bit trickier.
If you don't get any links, I will look at a few electronics places I should be passing by this weekend. If I find anything I'll let you know. I could always pick it up for you.
Take a look at
www.partsexpress.com for the hell of it. You may need to make one yourself - which isn't difficult. The parts should be available at an electronics store (I know they're all available at the place(s) I'll be going to tomorrow.
Bruno