We had a garage sale once about 15 years ago and I swore never again. I got so p*ssed off at people trying to bargain over 5 cents. Something would be marked 25 cents and people would say, "I'll give you 20 cents for it." Gimme a break... I'm a patient person and I don't mind someone trying to get a good deal, but it was ridiculous.
I was at a garage sale a few weeks ago and things haven't changed. There was a man who said, "I'll give you $20 for that water fountain." It was a HUGE cement water fountain and the seller said he'd take that. So, I watched the seller struggle to get a dolly under the fountain, move it and load it into the man's pickup. When time for payment the buyer said, "Would you take $10?" Mind you the fountain was now in the back of his truck...I swear I could've choked him myself. Then the seller got very angry. I didn't stick around to see the fight break out:>
So, be sure you've got the patience to deal with these kinds of people. I sure don't!