I once had someone try to haggle me for a $30 RRP toy that I was selling for $10 (he was demanding a 50% discount). When I told him that the price was already very cheap, he said that he couldn't afford it.
Mate... if 5 bucks makes or breaks a deal for you, then maaaaaaaybe you shouldn't be collecting toys? <shrugs> :/
I do sometimes haggle to, but I always ask, not demand. And I always make a proposal to benefit the seller, such as purchasing multiple items, instant payment with pickup etc. Some kind of benefit for the seller... not just asking for a discount for discount's sake. And I don't mind people haggling me for prices if they're going to offer something back (or I will even just throw in a discount or bonus goody if they are buying multiple items, even if they don't ask for it).
This is precisely why I despise shopping in a lot of Asian countries where they overprice goods and expect shoppers to haggle. Absolutely loathe it. This is why Japan is my favourite Asian shopping destination; the price that's advertised is the price you pay!