personally... I don't really haggle. I may if im buying multiple animals in the future but for now i've been buying single animals. But i ask if they have a package deal for multiples, rather than outright ask for lower prices.
What i generally do is look around (be it on the internet or at a show) and browse animals and prices. I'll walk around a show for 4 hours just looking and talking. IF i see something i like, i'll email the seller and see about shipping. If the animal is good enough quality for me to consider e-mailing a seller/breeder im usually happy with the price they are asking.
I paid 150 shipped for a 200g pastel male. Love him. Thats what the seller was asking, and i think my male qualifies as a pretty nice one.
When i got my spider, the seller was asking 350 shipped for a ~600 gram female spider. I thought the spider was a lovely animal (high white sides and minimal patterning are what i look for in my spiders) and the size was great. I asked if she could do her for 325, so i haggled for 25 on a 350 animal.
If an animal is really out of my price range either i save more money or look elsewhere. I really dont like super-haggling because i feel if someones produced a great quality animal, they should be paid what its worth.
man i hope that made sense lol :p