Did anyone find a solution all those years ago? My closest Chevy dealer (45 miles away) wanted $1200 to replace and install the radio. I bought one from a parts dealer on ebay for $180, and it took 5 minutes to replace. Now I see where the dealer thought they could get $1200 to do this.
See my signature for my full saga on replacing a head unit.
TL,DR: There are places that can unlock, but they don't always advertise. My dealer tried and failed to do it themselves, but found a place to do it (for like $250), and later I found a place online... though I had to call them, their site just said they "repair" radios, but once I talked to them they said they can remove VIN locks too. They might not be able to advertise this due to DMCA or something. Note that once you remove a lock, you probably have to re-program the unit to your car. If you are handy, it's probably cheaper to buy a VCX-nano and do this yourself, you'll pay the dealer that much anyway.