That's a great way to piss a seller off. The best price they're willing to give you is the highest price you're willing to pay. The seller already made their first offer with the listed price. Now it's your turn to make an offer. It takes two to haggle.

I don't haggle with bikes or anything cheaper. It's not worth the headache to save a few bucks. I'll haggle for cars, though. Even a small % off the asking price is a lot of money saved. Maybe a few bike's worth.