Quoted from CrazyLevi:"You are an idiot" and shoving price guides in their face is the wrong approach. For whatever reason they've got it in their head that they are sitting on gold and trying to convince them otherwise simply won't work.
The best thing to do is send them an email saying "Hey, I like your game but the market value on that is much lower...here's my offer. If you have no luck getting your price and would like to deal with me sometime down the line please contact me."
In the past I've had this work for me. Sometimes it takes months and sometimes you never hear back. But you won't get anywhere with a more aggressive approach.
I mostly agree, but start a little differently. Whether it's by email, phone or face to face, if the game is overpriced, I always start by asking if their price is negotiable. I've never gotten a quick no on a way overpriced game. They may think about if for a few seconds and kinda say no, but they never outright say no. Typically when a game is overpriced, they're guessing high and expect to sell at a lower price. Getting them to acknowledge that the price is negotiable sets the tone for your reasonable offer. They're expecting you to ask questions. Ask the most important one first. Break the price ice.
A link to Boston pinball has helped once or twice (via email), along with an explanation that games typically sell for more on ebay due to fees and wider exposure. Most reasonable people understand and accept this. The term 'undesirable title' has also gotten me some good deals. d
