I've bought and sold 60 games over the past 8 years, and never had this happen.
I saw an ad for a game I fancy on the facebooks.
I realized it was not far from where a friend of mine lives.
I asked my friend if he could go pick it up for me if I bought it.
He said sure, but not until early next week.
I messaged the seller and told him I'd buy the game if he would accept paypal payment and could hold it until next week.
He agreed to these terms.
I then asked for his paypal address so that I could send him the listed price.
He replied "In your original message to me you said you'd pay $100 more than the listed price".
I said no, I'll send you amount you listed it for, or you can sell it to someone else.
He said he had a guy coming to get it later on today, and if that fell through he'd let me know.
So, he was going to sell it out from under the next guy, if he could get $100 more from me.
Seems well more than shady.
I guess this highlights just how good the people in this hobby are, that I could have many deals over the years, and this is the first one that really made me angry with just how underhanded it was.
What's your worst story of an unscrupulous seller?