Ebay car stereos - BobbyG
I know this has been touched on with a thread in technical but article in today's paper caught my eye.

A guy in Liverpool was jailed for 15 months yesterday for stealing over 1000 car stereos and selling them on ebay over the course of 15 months. He apparently made over £229,000 ( a high average price I thought) by doing this.

We all know it goes on, we know it wouldn't if there wasn't a demand, but still an eye opener to see these figures I feel.
Ebay car stereos - AlastairW
If it wasn't ebay it would be the local paper or 'down the pub'. There will always be a market for such low lives. All you can do is buy from a reputable dealer (or brand new).
The fact it was in Liverpool is irelevant. Crime happens everywhere.