Motorola DynaTAC 8000X?

I don't know if anyone else is as crazy as I am, but I've considered purchasing one of these brick cell phones (first one for commercial use back in '83) and upgrading the internals to use it. I just got a BlackBerry so my previous Motorola flip phone isn't being used and I was thinking of things to do with it. I think it would be hilarious to put it into one of the old cell phones and wire it up so I can put in my SIM card and use it when I feel like it (I only want the calling function to work, not storing numbers or caller ID, etc). Has anyone done this? Where can I find one of the original DynaTAC phones? Ebay has showed up nothing.