Yep, I always ask 'How much for all of it'. I put the commons on my garage sale or send them to Al for homebrews. If you start sorting things out, it often prompts the seller to look more closely themselves.
Also, I've found that having some commons at my garage sale with 25 cents or 50 cents on them sparks conversations and often prompts people to drag their old stuff out of the attic for me to buy.
Believe me on first impressions it was a pile of shite, broken controllers and various leads with a couple of carts in the bottom, i'd already laughed off his £20 price as being ridiculous. Turns out one of his friends had been sales director for Atari in the UK and had given him all this stuff in the early '80s.