Well I did post a response to this thread earlier today, but because the site is not responding very well today it didn’t get posted.
I will try again.
Anyone who buys anything that “fell off the back of a lorry” isn’t going to care where it came from as long as the price is right and it works.
Passwords are easily overcome. Labels can be removed.
You could try a hot soldering iron and burn your name and address into the case somewhere, but you may have difficulty selling it legitimately if and when that situation occurs. (I did it once on a VCR but I found I couldn’t sell it when I wanted to)
The best bet is to back up everything on it on a regular basis and get it insured on a “New for Old” basis.
I think you would have to offer a very substantial reward to persuade someone to give it back to you.