Has this ever happened to you?

I have a few cars that I 'm parting out on here . I get a random PM from someone who asked if I'd sell the title , VIN plate and license plates off my parts car for a HEFTY sum. My gut reaction was no. And my final answer was no even after turning down his offer of $500.
Does this sound like someone "fishing" ? I must be honest and say for a moment that I thought the whole scenario out...The what if's....

My car is nothing special- Swinger, 318 auto puke green.
The amount offered seemed obscene. Gotta wonder (here comes the paranoid side of me out) if some Gov agency was fishing to see if they could hook some sucker into some illegal practice of selling VINS... OR is it?
Just looking for opinions regarding this and has it happened to you ?:???: