Where are they?

[kwacker]

I often see in mags and in tv programs breakers with hundreds of body panels hanging, and stacks of engines neatly sorted.

Where can I find one of these?

[bikerkeith]

Try the ads pages in MCN. If you need specific items there are sites that will connect you to most breakers around the country, so one call and then you just have to agree the price and pay for delivery.
Not used it myself but know others that have done so successfully.